CHAPTER 4

Horticultural Varieties of Citrus
BY ROBERT WILLARD HODGSON

HORTICULTURAL CLASSIFICATION
      In general appearance and other respects, the citrus fruits of principal commercial importance fall into four, reasonably-well-defined horticultural groups: the oranges, the mandarins, the pummelos and grapefruits, and the common acid members.   The common acid group includes three subgroups—the citrons, lemons, and limes.   While the writer's competence does not extend to all the citrus fruits that have horticultural importance, the considerable number with which he is acquainted all exhibit horticultural resemblances with one or more of these groups and subgroups that suggest some degree of relationship.   In most instances, it is not difficult to determine the group of closest resemblance and probable or possible relationship.   Therefore, in this treatment, for each of the natural groups presented there is a subsection covering fruits of horticultural importance that most closely resemble the group in question.   In some instances, however, lack of first-hand acquaintance with a fruit has necessitated provisional placement.
      In addition to the fruit groups mentioned above, all of which belong to the genus Citrus, there are the kumquats, which belong to the closely related genus Fortunella, and the so-called but much more distantly related trifoliate orange, Poncirus trifoliata (L.) Raf.   The kumquats comprise a group of considerable importance for their fruits.   The trifoliate orange, together with its hybrids, is of significance as a rootstock.
     The Oranges.—The principal members of the orange group are the sweet orange and the bitter orange, which though similar in many respects have important differences.
      Four kinds of sweet oranges are recognized:
      1. The common orange (blond orange of the Mediterranean), which is much the most important of the four and contains a large number of varieties.
      2. The sugar or acidless orange, which is of minor importance and so lacking in acid that it is insipid in flavor.
      3. The pigmented or blood orange, which is of considerable importance in Europe and includes two categories: (a) the light blood oranges; and (b) the deep blood oranges.
      4. The navel orange, which is of great importance and represented mainly by the Washington navel variety.
      The following three kinds of fruit are recognized among the bitter or sour oranges proper:
      1. The common bitter or sour orange that is used principally as a rootstock and for the preparation of marmalade.
      2. The bittersweet orange, the fruit of which is similar to the common bitter orange but less acid.
      3. The variant bitter oranges, grown primarily as ornamentals and for the flowers, from which neroli oil is extracted.
      Mediterranean fruits of horticultural importance that are obviously closely related to the bitter orange include:
      1. The myrtle-leaf orange or chinotto, grown mostly as an ornamental.
      2. The bergamot, grown primarily for its distinctive rind oil that constitutes the base of cologne water and has other perfumery uses.
      Oriental fruits that more closely resemble the bitter orange than any other include the Naruto and Sanbô of Japan, the Kitchli of India, and the Nanshôdaidai of Taiwan.
     The Mandarins.—Because of the remarkable diversity of the mandarins and the writer's lack of first-hand knowledge of many of the Oriental members, considerable difficulty was experienced in developing a satisfactory horticultural classification for this group.  In this treatment, therefore, the mandarins are presented in the following classes:
      1. The satsuma mandarins (Citrus unshiu Marcovitch), which are of great importance in Japan and consist of many varieties.
      2. The King mandarins (Citrus nobilis Loureiro), which have considerable importance in southeast Asia but contain few varieties.
      3. The Mediterranean mandarin (Citrus deliciosa Tenore), which is of principal importance in the Mediterranean basin.
      4. The common mandarins (Citrus reticulata Blanco), which have worldwide importance and are represented by numerous varieties.
      5. The small-fruited mandarins, which are of considerable importance in the Orient and consist of many varieties.
      The mandarin-like fruits include the synthetic tangors; the so-called natural tangor, Temple; many of the synthetic tangelos; the so-called natural tangelo, Ugli; and the Calamondin and Rangpur of the Orient, the latter of which includes the varieties Kusaie and Otaheite.
     The Pummelos and Grapefruits.—While similar in many respects and overlapping in certain characters, horticulturally the pummelos and grapefruits comprise separate classes, each of which consists of both non-pigmented and pigmented varieties.  Additionally, the pummelos contain both common acid and acidless or sweet varieties.
      Fruits that more resemble the grapefruit or pummelo than any other include a number of synthetic tangelos; the so-called natural orangelo, Chironja of Puerto Rico; the Poorman, Smooth Seville, and Wheeny grapefruit of Australia; and the Natsudaidai, Hassaku, Banokan, Hyuganatsu, Kinkôji, and Kinukawa of Japan; and the Attani of India.
     The Citrons.—The citrons, like the other members of the common acid group, fall into two classes—the acid and the sweet—each of which contains several varieties.
      Fruits more resembling the citron than any other include the so-called Cuban shaddock and Ponderosa lemon, the lumias of the Mediterranean, and the giant-fruited citrons of India.
     The Lemons.—The lemons, like the citrons, consist of the common or acid varieties,which are numerous and important, and the comparatively few and minor sweet or acidless varieties.
      Of the fruits that most closely resemble the lemons, those of principal horticultural importance are the limettas of the Mediterranean, the jamberi or rough lemon, the galgal and karna of India, and the so-called Meyer lemon of China.
     The Limes.—Like the citrons and lemons, the limes include both acid and sweet varieties,but in addition the sour limes consist of two kinds—the small-fruited Indian, West Indian, or Mexican lime and the large-fruited Tahiti or Persian lime, both of which have very few varieties.
      The lime-like fruits of principal horticultural importance include the synthetic lemonime, Perrine; several so-called lemons in India that appear to be natural lemonimes; and the bigeneric limequats (lime X kumquat), of which there are a few lime-like varieties.
     The Kumquats.—The principal fruits of horticultural importance or interest of the genus Fortunella are several kinds or varieties of the kumquat, the bigeneric, so-called orangequat, and the trigeneric citrangequats, of which there are a few varieties.
     The Trifoliate Orange.—Of the genus Poncirus, the trifoliate orange and some of its bigeneric hybrids—notably the citranges—are important primarily for their value as rootstocks.  A few of the citranges also approach edibility.
     

THE NATURE AND CONSTANCY OF CHARACTERS IN CITRUS
Fruit and Tree Characters
      In addition to the common characters possessed by other fruits, such as size, shape, color, form of the basal (stem) and apical (stylar) ends, flavor, and general seed features, the citrus fruits exhibit certain characters associated with: (1) the anatomy of the distinctive hesperidium fruit; (2) their degree of parthenocarpy; and (3) their degree of polyembryony.  Among the distinctive anatomical characters are those relating to the rind (flavedo and albedo) and inclusions (oil glands), the endocarp (fruit segments and juice vesicles), the central column or axis, and special structures that are or may be present in the apex (areole, mammilla, navel).  Seedlessness characterizes certain groups and varieties and monoembryony is exhibited by some.
      External Fruit Characters.—Citrus fruits range in size from very small to very large.  Among the smallest are the kumquats, Calamondin, and some of the acid limes, the greatest dimension of which may scarcely exceed an inch and a quarter (3 cm).  At the other extreme are the pummelo and citron which may attain a foot (30 cm) or more in diameter or length.  While the largest of the citrus fruits are pummelos, the heaviest are citrons because of their much greater rind density.  Some citrons attain weights of 10 to 12 pounds (approximately 4,500 to 5,550 grams).  Considering the citrus fruit groups as a whole, generally the oranges are medium-small to medium in size, the mandarins small to medium, the grapefruits medium-large to large, the lemons medium-small, the acid limes very small to small, the pummelos large to very large, and the citrons medium-large to very large.  The size range within each fruit group is variable, however, and is greatest in the mandarins, pummelos, limes, and oranges, each of which has varieties of smaller or larger size than the group average.  These are referred to as small-fruited or large-fruited varieties of each group.
      The shapes exhibited by the citrus fruits (fig. 4-1) range from round through subglobose and oblate to obovoid on one extreme and from broadly pyriform to ovoid, oblong, elliptical, and cylindrical on the other.  In general, the oranges are round or slight modifications thereof, the mandarins oblate, the grapefruits and pummelos subglobose, the lemons elliptical, and the limes oval.  The citrons are highly variable but mostly cylindrical, and some of the pummelos are pyriform.
      Superimposed on the general shape, and in some cases contributing thereto, are the basal and apical characters that may be present.  These characters may be rounded, flattened, or depressed in form, the latter form giving rise to a basin.  Likewise, they may be furrowed or ribbed.  Other basal characters that may occur include a neck, shoulder, or collar.  Other apical characters include the areole, which may be so indistinct that it is not evident, a nipple (mammilla), or a navel.  The neck character seems to occur oftenest in the lemons and mandarins and the navel most often in the oranges and mandarins.  The mammilla appears to be confined largely to the limes, lemons, and citrons.  In a few fruits, notably some of the citrons and the bergamot, a certain percentage of the fruits retain the style.
      The smoothness of the rind surface, which is highly variable, is in part determined by the size and position of the oil glands in the flavedo, which may give rise to small papillae or pits.  In addition, the rind may be rough, wrinkled, bumpy, or ribbed.  Most of the citrons exhibit the bumpy rind character, and many lemons are more or less ribbed.
      The primary color of the citrus fruits ranges from pale yellow to orange-red.  The limes, lemons, citrons, grapefruits, and pummelos exhibit varying shades of the former and the oranges and mandarins of the latter.  Superimposed on the primary color are various shades of pink or red exhibited by the pigmented grapefruits and pummelos and the blood oranges.
      Internal Fruit Characters.—For the most part, the internal characters of the citrus fruits are related to the distinctive structure of the hesperidium and concerned with the rind, fruit segments and inclusions, the central axis or medulla, and the seeds.
      For the citrus fruit groups as a whole, the range in both thickness and consistency of the rind is very great—from the extremely thick rind of some of the pummelos and the citrons to the very thin peel ofthe Indian acid lime, and from the soft, spongy nature of the albedo of the pummelo to the hard, dense fleshiness of the albedo of the citrons.  The range within each fruit group is also variable, giving rise to both thin-skinned and thick-rinded varieties.  The greatest range in rind thickness is exhibited by the pummelos, citrons, and mandarins.  Likewise, the range in degree of adherence of the rind to the fruit segments is very great—from the citrons, in which it cannot be separated by peeling, to the mandarins, in some of which it is almost completely loose at full maturity.
      Characters relating to the oil glands (in the flavedo) and their contents are also highly variable and appear to be distinctive for many of the citrus fruits.  These include the number, shape, size, arrangement, and position of the oil glands, and the kind, amount, and aroma of the oils.  Some of the aromas may be quite distinctive—fragrant as in the lemon or pungent as in the bitter orange.
      Among the principal characters of the edible portion of the fruit or pulp are the number of segments and the degree of their adherence to each other, the texture of the carpellary membranes, the form, size, and texture of the juice sacs or vesicles, and the color, amount, and flavor of the juice.  The number of segments averages highest in the pummelos, grapefruits, and citrons, and lowest in the kumquats, Calamondin, and acid limes.  The number of segments in the other fruits is intermediate.  Their attachment to each other is tightest in the citrons and loosest in the mandarins.  The juice vesicles vary greatly in size and form, somewhat in texture, and are distinctive for many of the citrus fruits.  In general, juice color corresponds somewhat with rind color, the range extending from pale green in the acid limes to deep orange in some of the oranges and mandarins.  Juice color is light to deep pink in the pigmented grapefruits and pummelos and may be dark red in the deep blood oranges.  The flavor of the juice varies greatly, depending principally on the total soluble solids content, the sugar-acid ratio, and the nature and content of essential oils.  Flavor ranges from insipid or flat to sweet, rich, or sour.  In some fruits, there is a characteristic mild to strong bitter aftertaste.  A pleasant aroma characterizes the juice of some of the mandarins and oranges.
      The size and solidity of the central column (columella or core) varies greatly at maturity and may be somewhat affected by climate and other factors.  In most of the citrons and pummelos, it is very large, while in the acid limes it is quite small.  In some fruits, such as the acid limes and citrons, the column retains its solidity as the fruit develops, whereas in the mandarins it breaks down early and at maturity all that remains are the vascular bundles which traverse it.  It may therefore be solid (closed), semi-solid, or hollow (open).  One of the distinctive differences between sweet and bitter oranges consists in the much greater degree of openness of core exhibited by the latter.
      The seed content of citrus fruits is highly variable and for some groups and varieties constitutes a distinctive character, although it may also be affected by climate and other factors.  Thus, the navel oranges, satsuma mandarins, and a few other varieties are usually seedless, since they rarely produce viable ovules and pollen.  Even though viable pollen is produced in abundance, many of the principal varieties regularly produce few or no viable ovules and hence are commercially seedless (none to ten seeds).  When self-pollinated, some varieties are nearly seedless, whereas they are seedy when cross-pollinated.  In the seedy varieties, the number of seedsmay range from one to four or more per fruit segment.
      The seeds are highly distinctive for the different citrus fruits and vary greatly in size, shape, surface texture, and somewhat in color.  Internal characters include color of the inner seed coat, the chalazal spot and cotyledons, and the degree of polyembryony.  The pummelos and citrons are regularly monoembryonic, whereas the grapefruits, Indian acid lime, and many of the mandarins are highly polyembryonic.  The oranges and lemons are usually intermediate.
      Tree Characters.—Normal season of maturity is a varietal character of great importance that is determined by the interaction of the environment and the total heat requirement of the tree.  While, as might be expected, the citrus fruits as a whole are characterized by a wide range in heat requirement for fruit maturity, some of them—notably the mandarins and sweet oranges—exhibit surprisingly large differences in varietal heat requirement.  As a consequence, there are very early, early, midseason, and late-maturing varieties for both of these fruits, extending over a maturity period of several months.  Of importance in this connection is still another varietal character determined by the tree: the ability to hold or store the fruit for a lengthy period without appreciable impairment in quality or loss from dropping.  The Valencia orange variety is outstanding in this regard.
      The range of variation in tree growth habit exhibited by the citrus fruits as a whole is very wide—from the straggly, shrub-like citron to the large, highly symmetrical trees of most of the sweet oranges and grapefruits and some of the mandarins.  Within each fruit group, however, the range of growth habit is highly variable.  The grapefruits and sweet oranges show the narrowest range and the mandarins the widest.  Certain varietal groups, such as the satsuma mandarins and navel oranges, are characterized by growth habits so distinctive that they are useful in identification.  This is true also of certain groups of lemon varieties, with particular reference to vigor, density of foliage, and degree of thorniness.  In addition, some varieties of oranges and mandarins have leaves of distinctive size, form, color, or other features.
      Descriptive Terms, Definitions, and Forms.—Because it remains the best presentation available in English and may therefore be of value to teachers, students, and technicians, Webber's (1943) outline for the description of citrus fruits is reproduced.
      The foregoing outline is designed for use as a printed blank.  Under each heading the most common descriptive terms are given so that in describing a fruit sample the terms applying can be checked.  If the fruit varies in a certain character, the two or more descriptive terms applicable should be checked.  The outline is clear in most details, but a few characters may require explanation.  Definitions of most of the terms used may be found in botanical glossaries and dictionaries.
      Color should be carefully compared when possible with some standard color charts, such as those of Ridgway (1912).
      The D/H index given under size is obtained by dividing the diameter of a fruit by its height (distance from stem to apex).  The average D/H is obtained by totaling the indices of all the individual fruits measured and dividing by the number of fruits.
      The descriptive terms applied to the base of citrus fruits willbe readily understood by an examination of figure 4-2.
      The areole is the area at the apex of the fruit which is usually set off by a more or less distinct circular furrow surrounding the stylar scar.  In descriptions, the circular furrow is referred to as the areole and the area within it as the areolar area.
      The inner seed coat is the membranous covering under the thick, leathery exterior coat.  The chalazal spot is the round area on the inner seed coat at the chalazal end of the seed, which commonly is characteristically colored.
      The work of Chapot (1955a) in the descriptive pomology of the citrus fruits is outstanding.  His monograph on seed characters in Citrus (Chapot and Praloran, 1955) is a contribution of great importance and significance, as are also his numerous other papers.

Constancy of Characters
      While the botanical characters relating to the leaves, flowers, fruits, and seeds are sufficiently distinctive and constant to permit relatively easy determination of species, botanical varieties, and certain subspecies groups, these characters nevertheless exhibit a considerable degree of variability.  Horticultural characters of both tree and fruit, by means of which varietal identification can be made, are extremely variable, however, and many of them are highly lacking in constancy.  This results in numerous citrus fruit varieties which are distinguishable with difficulty, if at all.
      Since constancy of citrus characters varies greatly, descriptions overlap slightly and identification may be somewhat blurred.  Such tree characters as distinctive growth habit, comparative season of fruit maturity, and ability to store the fruit on the tree are relatively stable and constant in a subtropical climate.  As would be expected, the most constant fruit characters are those related to the special anatomical features of the fruit: the presence or absence and nature of the areole, mammilla, or navel.  Degree of seediness and comparative acidity of the juice are variable, of course, but still reasonably constant.  Comparative size and form of the fruit, comparative color, and thickness and adherence of the rind, while highly variable among varieties, exhibit a reasonable degree of constancy within a variety and hence are useful.
      Some citrus tree characters and most fruit characters are markedly affected by environmental influences.  Indeed, these are of very great importance, for they largely determine the distinctive characteristics of the fruit upon which market reputation and consumer preference are based.  The principal environmental influences undoubtedly are climate and rootstock.  Soil type and cultural practices may also affect fruit characteristics, although usually to a minor degree.
      Climatic Effects.—Among tree characters, period of fruit maturity is undoubtedly of greatest importance and is determined by the nature of the climate.  Thus, the Valencia orange is horticulturally mature by January in the very hot, dry, low-elevation desert of southern California, but does not attain maturity until the following June in the cool, mild, equable coastal valley regions.  Ability of trees to hold their fruit is also affected by the nature of the climate during and after maturity; this character is minimized by warm night conditions after maturity.  Even certain aspects of tree growth habit—compactness of tree and density of foliage—are influenced by climate; these tendencies are accentuated in dry and very cool climates.
      The effects of climate factors on fruit characters are much more striking, however, and are sometimes remarkable.
      While there are numerous factors that may affect fruit size, climatic conditions characterized by high heat and humidity during the growing season make for large fruit.  Thus, the large-fruited Washington navel orange, which attains ideal size in California, reaches undesirably large size in the humid, semitropical climates which characterize Brazil and Florida.  In contrast, the small-fruited Hamlin orange never attains a commercially acceptable size in the arid, cooler subtropical climate of the southern California coastal region but does become sufficiently large in Florida and Brazil.  In this general connection, it may be pointed out that the "small fruit" problem is restricted to medium-sized varieties in arid regions and in seasons of marginal or below average heat, whereas the "large fruit" problem is confined to large-fruited varieties in regions or in seasons of above-average heat or humidity.
      Fruit form may be profoundly modified by climatic factors.  In general, the axis is longer in regions of low atmospheric humidity, and vice versa.  Thus, an oval variety, such as Shamouti orange, may range from short-oblong (almost round) to long-elliptic depending on climate.  Likewise, the average shape, within any given round variety of orange, may range from subglobose to oblong, with accompanying differences in diameter-height (D/H) index from well above 1 to considerably below that value.  The factors which function to increase length of the fruit also appear to favor or accentuate the tendency to develop a neck in the mandarins and a pyriform shape in the grapefruits.  Therefore, the same variety may exhibit significantly different fruit forms in regions of different climatic conditions.
      It has long been recognized that color is markedly affected by the temperature regime during the ripening period and thereafter.  Maximum color intensity develops when the fruit is subjected to considerable chilling—normally the result of cold nights.  In arid, subtropical climates, this is assured by the prevalent cool nights (associated with the wide diurnal fluctuations in temperature) which characterize the fall and winter months.  Primarily because of warmer nights (associated with small diurnal temperature variations), color development in semitropical climates is much slower and the intensity ultimately attained considerably lower, with the possible exception of some of the mandarins, notably Dancy tangerine.
      Other fruit characters materially affected by atmospheric humidity during the growing season include rind surface, thickness, texture and adherence, texture of the flesh (juice vesicles and carpellary membranes), and juice content.  Thus, in semitropical regions such as Florida, the rind is smoother, thinner, softer, and more tightly adherent, the flesh and carpellary membranes are tenderer, and the juice content is higher than in such subtropical regions as California.
      Flavor is markedly influenced by the same conditions that are primarily responsible for the intensity of color development, namely, degree of fluctuation between day and night temperature.  Wide diurnal fluctuation appears to promote sugar accumulation and acid formation, and vice versa.  In general, therefore, the fruit grown in arid subtropical climates is more strongly and richly flavored than that produced in semitropical or tropical climates.  Fruits or varieties that are characterized by relatively high acidity, however, such as the kumquats and some of the mandarins (for example, King and Kara) and their hybrids (for example, Temple tangor and Minneola and Seminole tangelos) are more pleasantly flavored in semitropical or tropical climates, and vice versa.  The same seems to be true with respect to the bitterness that characterizes most of the grapefruits and some of their hybrids (notably Sampson tangelo).  Since individual tastes differ so greatly, it is meaningless to argue as to the superiority or inferiority of one over the other.  The important fact is that they exhibit distinctive differences.
      Likewise, the characteristics of the areole, mammilla, and navel are subject to climatic modification.  In general, these modifications are more pronounced and prominent in arid than in humid climates.  In the hot semitropics, the areolar furrow, which may be prominent in the arid subtropics, is usually absent and the nipple much less well developed or even suppressed to the degree that it is scarcely discernible, if at all.  In subtropical regions, it has long been recognized that the size and prominence of the navel in the navel oranges varies considerably among climatic zones, from season to season, and even between the exterior and interior parts of the tree.
      A most remarkable illustration of the interactions between climatic factors and fruit characteristics is afforded by the Nagpur mandarin in central India, where climatic conditions induce the production of several periods of bloom peryear and, thus, provide a choice of the bloom to be employed—spring or fall.  Many of the growers use the spring bloom for part of the orchard and the fall bloom for the remainder.  The characteristics of the fruit in the two crops are remarkably different.  The spring-bloom fruit is larger, flatter in form, paler incolor, and notably less acid.  Its sugar-acid ratio averages approximately double that of the fall-bloom fruit.  Bonavia (1888-90) has described numerous other more striking illustrations in India, where there is doubtless a wider range of citrus species and forms and of climatic conditions than exists elsewhere.
      Another less spectacular illustration is exhibited by the lemon, most varieties of which have two principal periods of bloom—spring and late summer or early fall—but are more or less everflowering and everbearing.  In Italy, the crops resulting from the flowers produced at various times during the year have been named and accurately described (Casella, 1935b).  There are clearly greater differences between some of them, notably Primofiori (spring) and Verdelli (summer) than between many lemon varieties.
      Rootstock Effects.—Although rootstocks may effect growth habit to some degree, their principal effects on tree characters are concerned with period of fruit maturity and ability of the tree to hold or store the fruit.  On certain rootstocks, notably the rough lemon and Indian or Palestine sweet lime, the acidity attained by most citrus fruits is significantly reduced as compared to such common rootstocks as sour or sweet orange.  As a consequence, on these rootstocks maturity is advanced as judged by taste or measured by the sugar-acid ratio.  The flavor is not rich, however, for the total soluble solids content of the juice is likewise usually low.  On certain other rootstocks, notably trifoliate orange, the soluble solids are significantly increased, with the result that although a corresponding sugar-acid ratio is attained at approximately the same period the fruit has a richer flavor.  Earliness of commercial maturity, as measured by either the sugar-acid ratio or acid content of the juice, may therefore be markedly affected by the rootstock employed.  Closely associated with these effects is the ability of trees to hold or store the fruit.  The rough lemon as a rootstock causes the fruit to lose quality—both juice content and flavor—and to drop earlier than normal, whereas the bitter orange as a rootstock seems to prolong the period of satisfactory storage on the trees.
      Theprincipal fruit characters that may be affected by rootstocks include size, color, rind thickness, juice content, and flavor.  Thus, orange size is usually somewhat larger on the trifoliate and bitter orange rootstocks and smaller on sweet orange.  Color is sometimes paler on the rough lemon and Palestine sweet lime rootstocks and the thickness of rind is generally greater, with a corresponding reduction in juice content.  And, as brought out above, flavor is richer on certain rootstocks than on others.  With the exception of flavor, however, rootstock effects on fruit characters are usually less marked than those caused by climatic factors.
      Soil Influences.—That the soil may affect tree characters and fruit characteristics is a belief of long standing that finds support in observational evidence.  It appears that average fruit size is larger and maturity is slightly earlier on the lighter-textured soils, but that the color is likely to be paler, the rind thicker, and the flavor poorer.  And it is generally agreed that the fruit holds on the trees better on the finer-textured soils.
      Soil differences are usually small, however, unless accentuated by rootstock effects.  Thus, the undesirable influences of the rough lemon rootstock are increased by sandy soils and reduced slightly by silty soils.
      Limitations of Descriptive Pomology.—From the foregoing, it is clear that the horticultural characters concerned in the identification and description of citrus fruit varieties are so variable and subject to such profound environmental modification that the problems presented are difficult indeed.  Thus, on the basis of fruit characters alone it isimpossible to identify many varieties.  And it is difficult or impossible to accurately identify numerous varieties on the basis of both tree and fruit characters.  It is highly probable that there are far fewer varieties than the lists available indicate.  This is further suggested by the absence of comprehensive and dependable varietal keys for countries and regions where citriculture has been practiced longest and where varieties are most numerous.
      With regard to varietal description, even though the sampling provides representative materials, it is obvious that detailed and exact descriptions are accurate and meaningful only for a given environment or similar conditions of climate and rootstock.  Thus, descriptions of the same varieties in different countries or states often fail to correspond in important respects.  Perhaps the best illustration is afforded by the differences between Florida and California varieties.  Detailed descriptions of Florida varieties grown in California are far from accurate for Florida conditions, and vice versa.

VARIETAL DEFINITIONS AND MODES OF ORIGIN
      Irrespective of mode of origin and method of reproduction or multiplication, a horticultural variety (cultivar) consists of a named or otherwise designated group of plants representing one of the many genetically different kinds of any given cultivated plant species or botanical variety (Frost, 1943, p. 837).  In citrus, as with most other fruits, a horticultural variety traces back to a single parent tree or individual mutant branch which has been multiplied by vegetative or asexual means, such as cuttage or graftage.  To provide a more precise name for a group of such plants, Webber (1903) introduced the term clone.  Citrus varieties or cultivars are therefore clonal varieties.
      Complicating the situation to some degree is the fact that in most citrus varieties the existence of the phenomenon of polyembryony makes available apomictic seedlings of nucellar origin.  These are genetically identical with the seed parent, but may exhibit physiological differences of some magnitude and duration that apparently relate to age from seed propagation and diminish with time until they ultimately disappear.  These probably should be regarded as juvenile characters.  Because of these differences, it has become desirable to distinguish between the parent, original, or "mother" clonal selection or budline and the nucellar or "daughter" clonal line of the same variety.  For various reasons, in California and increasingly so elsewhere in the United States, nucellar or young clonal budlines or selections are rapidly displacing parent or old clonal budlines, and this trend seems certain to extend to other countries.
      Another complicating factor is the existence within certain varieties, notably among lemons in California, of slight but consistent variations that can be detected with certainty only by growing considerable numbers of trees of different progenies in close proximity.  These differences are evident mainly in comparative habit of growth, vigor, density of foliage, and sometimes in fruitfulness.  Presumably, such variations have arisen as seedlings or undetected budsports, principally the latter, and have unintentionally been propagated.  Since the differences are small and detectable with difficulty, they have commonly been referred to as strains.  While this type of delineation is well established in California, and to some extent elsewhere, and may appear to have certain advantages, it is technically incorrect according to the International Code of Nomenclature for Cultivated Plants (Anonymous, 1961, p. 13).  So-called strains which exhibit desirable characteristics and are considered worthy of distribution therefore should be given varietal designations irrespective of origin or degree of resemblance to already named varieties.
      The selection and naming of outstanding old bearing trees as sources of propagation materials is currently widespread in California and to some extent elsewhere, having been greatly stimulated by the extensive studies initiated about 1909 by Shamel (1943) and his associates.  Unfortunately, these old bearing selections have commonly been incorrectly referred to as strains instead of clonal selections or budlines.  Almost without exception they have been found to be identical with the variety in question.  Whatever differences in behavior they may have exhibited, if any, are attributable to the nature and degree of virus orother infections they carry.  There have been a few such selections, however, that apparently are different and represent undetected bud variations in the parent tree or an error in its bud parentage.  These are in reality new or different clonal varieties.
      In common with other fruits, citrus varieties may originate as chance seedlings, budsports (somatic mutations), or hybrids resulting from plant breeding.  Most of the varieties currently grown doubtless originated as chance seedlings.  This is known to be true for most of the orange and grapefruit varieties discovered in Florida.  This mode of origin is no longer operative to an important degree, however.  Some varieties are known to have originated as limb sports, notably numerous navel orange and satsuma mandarin varieties and the pigmented grapefruit varieties.  A few promising varieties resulting from breeding programs in Florida and California have been introduced and others are in prospect.
      The early literature (Han Yen-chih [1178], 1923; Ferrari, 1646; and Bauhin, 1650) does not indicate specific recognition of the horticultural variety concept, although it is suggested by descriptions of numerous kinds of oranges, mandarins, lemons, and citrons, and references to the budding and grafting of seedling trees.  By the nineteenth century, however, there can be little doubt that the concept was recognized, since Gallesio (1811) described accurately eight kinds of orange and Risso and Poiteau (1818-22) described and figured forty-two varieties of citrus fruits.
      The first relatively adequate horticultural classification of the citrus fruits and description of their varieties in the United States is that of Hume (1904, 1926) and the most recent and comprehensive that of Webber (1943).  In California, Spalding (1885) was perhaps the first to attempt the listing and description of varieties, followed shortly by Lelong (1888), who presented much more detailed and accurate characterizations.  For descriptions of Mediterranean varieties, the reader is referred to Casella (1935a), Rebour (1950), and Gonzalez-Sicilia (1963).

THE PRINCIPAL VARIETIES AND THEIR MOST DISTINCTIVE CHARACTERISTICS
      Because of the remarkable potency of environmental influences on citrus fruit characters, detailed varietal descriptions will not be attempted.  Instead, the objective is to present the most distinctive characteristics that will be helpful in identification and evaluation.  Insofar as practicable, this is done for all varieties currently of commercial importance or likely to become important.  Less detailed treatment is given to varieties of declining or limited local importance.  Lack of information requires that for many such the characterizations be sketchy and incomplete.
      The sources of information used include the personal knowledge of the author based on observation and study of the principal collections in the United States and considerable travel abroad, the literature of the past four decades, and personal communications from horticulturists in many parts of the citricultural world.
      The horticultural classification employed in the sections that follow is that of the author and is outlined at the beginning of the chapter.  Obviously, it is both arbitrary and empirical in considerable degree and hence subject to valid differences of opinion.  Since the classification is based primarily on resemblance, it has seemed best to place the known and presumed hybrid varieties in those groups they most resemble, irrespective of parentage, known or presumed.  In some cases, resemblances are so tenuous that classification is difficult and provisional, and in others lack of information may prove responsible for errors.
      For the most part, the botanical nomenclature used is that of Tanaka (1954), whose system though excessively detailed is much more comprehensive than the rigidly restricted classification of Swingle (1943) and hence, in the opinion of the writer, more useful.  However, the use of Tanaka's binomials is primarily for the convenience of the reader and should not be interpreted as an unqualified acceptance or endorsement of his classification in toto.  Indeed; on the basis of the natural groups and horticultural varieties with which the writer is personally acquainted he cannot accept a number of the species in question.  Moreover, he frankly disclaims competence to pass judgment on many others.  It is his general conclusion, however, that these two classification systems represent extremes and that somewhere between them there will ultimately emerge a more supportable and generally acceptable system of botanical classification and nomenclature.
      With the exception of those varieties whose origin is unknown, such as the Valencia orange, or which are widespread under names given elsewhere than in their country of origin, such as the Washington navel orange, the names used are those employed in the respective countries of origin or their English equivalents.  The principal synonyms are given in parentheses.  Insofar as practicable, the varieties described in the following sections are presented in two groups for each fruit: major and minor.  Major varieties are those currently of principal economic importance or which because of their promise seem likely to become so.  Minor varieties are those currently of comparatively little importance or primarily of historical or other interest.  Within each group, the varieties are listed in alphabetical order.

THE SWEET ORANGE (CITRUS SINENSIS [L.] OSBECK)
      In common with most of the other citrus fruits of commercial importance, the sweet orange appears to be native to the region comprised by northeastern India and adjoining portions of China and Burma.  It appears to have been first grown commercially in southern China.  Its cultivation in the upper Mediterranean basin has generally been considered to date back to approximately the middle of the fifteenth century; not long thereafter it reached the Western Hemisphere.  However, Tolkowsky (1938) has adduced evidence of a much earlier European introduction (200-300 A.D.).  The sweet orange is the naranja of Spain, arancio of Italy, laranja of Portugal, orange of France and English-speaking countries, the malta of India, and kan of Japan.
      The sweet orange is dominant in the citricultural world, since, with the exception of the Orient where the mandarin is preferred, no other citrus fruit is so universally liked and used.  It is much more widely distributed and grown than any other and currently comprises about two-thirds of the total world production of citrus fruits, which in 1965 was almost 600 million 70-pound box equivalents, and is increasing rapidly.  The United States was much the largest producer of oranges with approximately 121 million boxes followed by Spain (55 million), Brazil and Italy (24 and 37 million, respectively), Mexico and Argentina (24 and 20 million, respectively), Israel (23 million), and Morocco and South Africa (16 and 15 million, respectively).  Six other widely-distributed countries produce 5 million to 10 million boxes annually and eleven others a million boxes or more.  The remaining citrus fruits are produced by about two dozen other widely distributed countries.  Moreover, both planting and production will certainly increase during the coming decades.  As this chapter went to press in 1967, the Florida orange crop alone was estimated at 143 million boxes.
      With the exception of the mandarin and bitter or sour orange, the sweet orange tree is the hardiest of the citrus fruits of commercial importance.  The mandarin fruit is much more susceptible to frost injury, however.
      In most parts of the world, the sweet orange is still used primarily as a fresh fruit for eating out-of-hand or serving as a dessert.  In the United States, however, and increasingly so elsewhere, the principal use now is for the juice, which is extracted and served fresh or preserved by chilling, pasteurization, and concentration (see chap. 2, p. 47 [text version, Revised Ed.]).  The single-strength canned juice now available is a reasonably satisfactory substitute for freshly expressed juice and keeps relatively well.  Much the best product, however, in that it is acceptable as a substitute to all but the most discriminating palates, is the frozen juice concentrated under vacuum, which of course, requires freezing storage.  The consumer acceptance of this product has been phenomenal, and much the greater part of the Florida production is now utilized in this form.  The use of oranges for juicing, enhanced by the spectacular success of frozen concentrate, has materially increased the consumption of oranges in the United States and brought about greatly increased production in Florida.
      Valuable byproducts are also obtained from the rind of fruit sent to processing plants for juicing.  Principal byproducts are essential oil, pectin, and cattlefeed.
      The sweet oranges naturally fall into four kinds: the common oranges, acidless oranges, pigmented oranges, and navel oranges.  They may also be distinguished on the basis of season of maturity as early, midseason, and late.  In some of these groups, possibly all, there are variegated varieties of local importance as ornamentals, such as the dwarf variety Fuya Menuda.

Common Oranges

      These comprise the ordinary or common oranges which in the Mediterranean basin are referred to as the white or blond orange (blanca of Spain, biondo of Italy, blonde of France) to distinguish them from the pigmented or blood orange.  The characteristics of the common oranges are so well known as scarcely to require comment.  Indeed, the distinctive color—a combination of red and yellow—has for centuries been used as the common name of this fruit, in which connection it may be of interest to note that yellow-fruited orange varieties have long been known (such as the Prata of Spain and Tenerife of the Canary Islands).
      In most of the older orange-producing countries, there still remains a considerable production of sweet oranges from seedling clones grown either as seedlings or budded trees.  In Spain and Italy, these are usually referred to as comuna or comune (Biondo di Spina or di Arrudi), respectively, and in Florida as Florida Common.  In North Africa and the Near East, they are called beladi or beledi (various spellings), bizri (when grown as seedlings), and Bordugal (Portugal).  They are known as criolla in Argentina and Uruguay, caipira in Brazil, and corriente in Mexico.  And finally, in South Africa and Australia, they are called Cape Seedlings and Paramatta Seedlings, respectively.
      In general, the seedling clone trees are vigorous, large, somewhat thorny, productive, and long-lived, but the fruit is commonly coarser in texture and seedier than most named varieties.  With minor exceptions, the propagation and planting of these seedling clones has been abandoned in favor of better, named varieties.  It must be remarked, however, that under certain conditions these seedling clones are sometimes more profitable than the named varieties available and hence will continue to be used.  So long as they remain profitable, there is little incentive for growers to replace such orchards.
      As might be expected, the common sweet oranges are the most widely grown and commercially the most important of the four kinds of sweet oranges.  There is reason to believe that they constitute about two-thirds of total orange production.
      They are not only the oldest, largest, and most extensively cultivated kind of sweet oranges, but they include more varieties than any other.

     Major Common Orange Varieties.—Descriptions are presented below of those common orange varieties grown on an extensive scale, increasing in importance, or which the author believes have qualities of major significance.

Barão
      Fruit medium-small, ovoid to oblong; base with occasional radial furrows; seeds comparatively few.  Rind medium-thick and surface smooth.  Color deep orange when ripe.  Flesh well-colored; coarse, firm in texture; juice content below average; flavor rich and sweet.  Medium early in maturity.
      Tree vigorous, upright, medium-large; foliage dense; very productive.
      This Brazilian variety (Moreira and Filha, 1963) is of unknown origin, presumably a chance seedling, and does not meet the requirements of the processing industry or export trade.  It is said to be much appreciated by the Brazilian populace.

Bedmar
      See under Berna.

Belladonna
      Fruit medium-large, oblong to oval; base commonly with small, slightly furrowed basin; areole faint or lacking; seeds few or none.  Color deep orange at maturity.  Rind medium-thick, tightly adherent as are also the segments; surface finely to coarsely pebbled.  Flesh moderately juicy and flavor pleasant.  Early midseason in maturity, but holds well on tree for several months.  Stores and ships well.
      Tree vigorous, medium to large, symmetrical, and productive.
      An old Italian variety of unknown origin, Belladonna is widely grown in Italy and ranks second there only to Calabrese.
      According to Casella (1935a), the fruits of Belladonna and Calabrese have close resemblances, but the former averages larger, is better colored, and has a thicker and somewhat coarser rind.  The season is altogether different as are also the trees.  Both varieties are of excellent quality.

Berna (Bernia, Verna, Vernia, Verda, Bedmar) (fig. 4-3)
      Fruit medium-small, oval to ellipsoid; base commonly with faint radial furrows; apex slightly depressed; seeds few or none.  Well-colored at full maturity, but regreens thereafter.  Rind medium-thick, firm; surface finely pebbled.  Flesh well-colored; moderately juicy; flavor sweet.  Fruit holds especially well on tree with good quality and ships well.  Late in maturity, but earlier than Calabrese of Italy and Valencia.
      Tree slow-growing, compact, medium-small in size, and slow to bear but productive.  Somewhat inclined to out-of-season flowering and production of worthless off-season fruits.  Usually has a few long and narrow leaves.
      This distinctive variety is of Spanish origin but is grown also in Morocco and Algeria.  It is one of the latest maturing of all Mediterranean varieties and holds on the trees as well as Valencia or better but is smaller and of poorer quality.
      Several clones of the Berna are recognized, one of which is characterized by greater tree vigor and round fruit of higher juice content.  A selection named Alberola is said to be of superior quality.  A highly similar, if not identical, variety is Peret.

Biondo Comune (Nostrale Liscio)
      Fruit medium to medium-large, subglobose to round; basal cavity small and deeply furrowed; apex flattened or slightly depressed; seedy.  Color yellowish-orange at maturity.  Rind medium-thick and surface finely to moderately pebbled.  Flesh very juicy and flavor pleasant when fully mature.  Medium early in maturity, but holds well on tree and ships well.
      Tree vigorous, hardy, large, and productive.
      One of the oldest Italian varieties and of unknown origin, Biondo Comune has been little planted in recent decades and doubtless will ultimately disappear.  It still comprises the bulk of production of common sweet oranges in some of the oldest Italian districts.

Biondo Riccio
      Fruit large, globose; base slightly flattened and deeply furrowed; apex slightly depressed; seedy.  Well-colored at maturity.  Rind medium-thick and surface coarsely pebbled and somewhat rough.  Flesh juicy and flavor pleasant when fully ripe. Medium early in maturity and ships reasonably well.
      Tree moderately vigorous, highly productive, and hardy.
      Another very old Italian variety of unknown origin, Bionao Riccio has not been planted for years but is still important in some of the oldest Italian districts.

Biondo di Spina
      See under common oranges.

Cadenera (Cadena Fina, Cadena sin Jueso, Orero, Valence san Pepins, Precoce de Valence, Precoce des Canaries) (fig. 4-4)
      Fruit medium-sized, globose to slightly oval; apex somewhat depressed; areole ring faint or lacking; seeds few or none.  Moderately well-colored.  Rind medium-thin and surface smooth to finely pebbled.  Flesh very juicy and flavor and aroma excellent.  Holds well on tree and retains quality.  Medium-early in maturity (preceded by Salustiana and Hamlin).
      Tree vigorous, hardy, large, and productive.
      Of Spanish origin, presumably a chance seedling, Cadenera appears to be the most important variety in Spain, its production being exceeded only by only by comuna, which, as noted earlier, consists of a group of unnamed similar or identical seedling clones.  It is important also in Morocco and Algeria and hence ranks high among major orange varieties.  Because of its excellent quality, it is well and favorably known in European markets.
      Cornice appears to be a selection of Cadenera (Chapot, 1948) but Cadena Punchosa is an inferior variety no longer being planted.

Calabrese (Ovale) (fig. 4-5)
      Fruit medium-large, oval; base commonly with low, narrow, slightly furrowed collar; areole faint or lacking; seeds few or none.  Well-colored at maturity, but regreens if held on the tree long thereafter.  Rind medium-thick, very tightly adherent; surface finely pebbled.  Flesh juicy and well flavored at maturity.  Holds especially well on tree with little loss in quality and stores and ships well.  Late in maturity (the latest of Italian varieties and approaching Valencia).
      Tree of good vigor and size, slow growing, somewhat irregular in form; leaves light-green and of somewhat distinctive color and appearance.  Pronounced tendency to produce out-of-season bloom and fruit.  Sensitive to cold, heat, and desert winds, but productive under favorable conditions.
      Calabrese is the preferred name to distinguish this important variety from others of oval form.
      Of unknown origin, this old Italian variety is widely grown and for decades has ranked as first in importance among common sweet orange varieties in Italy, a position it seems destined to maintain because of its many excellent features.

California Mediterranean Sweet
      See under Maltaise Oval.

Castellana
      Fruit medium-sized, subglobose to spherical; moderately seedy.  Color light orange.  Rind medium-thin and surface somewhat granular.  Flesh color pale; juice abundant, low in acidity; flavor sweet.  Holds on tree moderately well but loses quality.  Medium early in maturity.
      Castellana is said to be the principal variety in the Almería Province of Spain where it matures earlier than elsewhere.  It is no longer being planted, however.

Clanor (Clanwilliam, Clan William)
      Fruit medium-large, globose to oblong; seeds relatively few.  Rind medium-thin, tough, leathery; surface moderately pebbled.  Flesh melting, juicy; flavor good.  Late midseason in maturity.
      Tree vigorous, upright in growth habit; foliage dense; a regular and heavy bearer.
      This South African variety from western Cape Province traces back to two apparently identical trees in the 30-year-old William van Wyk orchard of the Kanolvlei farm that had been layered from old Clanwilliam seedling orange trees on the Rondegat farm.  The selection was made by P.  Nortier of Clanwilliam in 1930.  Clanor has gained rapidly in popularity and currently is recommended as one of the best midseason varieties for planting in South Africa.

Clanwilliam
      See under Clanor above.

Garey's Mediterranean Sweet
      See under Pope.

Glen Summer
      See under Pope.

Hamlin (Norris) (fig. 4-6).
      Fruit medium-small, globose to slightly oblate; sometimes with low radially furrowed collar and faint areolar ring; seeds very few or none.  Well-colored at maturity (one of the best in Florida).  Rind thin, with smooth, finely pitted surface.  Flesh well-colored; tender, juicy, lacking in acid; flavor sweet.  One of the earliest to mature.
      Tree moderately vigorous, medium-large, productive, and more cold-tolerant than most.
      The Hamlin variety originated as a chance seedling in an orchard near Glenwood, Florida, which was planted in 1879, and was named for the owner, A. G. Hamlin, at the time its value was recognized some years later.  It came into prominence following the great Florida freeze of 1894-95 as a rival of Parson, the only other variety of similar early maturity, and has gradually replaced it.  Currently, it is a major variety in Florida, of considerable importance as an export variety in Brazil, of limited importance in South Africa and elsewhere, and possibly the world's principal variety of very early maturing common sweet orange.
      In semitropical climates characterized by high heat and humidity, this variety produces fruit of satisfactory size for marketing fresh, although the eating quality is generally somewhat disappointing.  In arid, subtropical climates, fruit size is commonly smaller than desirable though the quality may be satisfactory.

Hart's Tardiff
      See under Valencia.

Hitmali
      See under Khettmali.

Homosassa
      Fruit medium-sized, subglobose to ellipsoid; base evenly rounded to slightly collared and basal area somewhat furrowed; apex evenly rounded; areolar furrow indistinct or lacking; moderately seedy.  Well-colored at maturity.  Rind medium-thick, smooth, and finely pitted.  Flesh medium-tender, juicy; flavor good.  Midseason in maturity.
      Tree vigorous, large, productive, and hardy.
      According to Webber (1943), Homosassa isone of the oldest Florida varieties, having originated as a seedling selection in the orchard of a Mr. Yulee at Homosassa.  The selection must have been planted not later than 1865, for in 1877 the Variety Committee of the American Pomological Society recommended it as a first-class variety.  It was extensively planted for some decades, and there are old orchards still in existence.  Like certain other Florida varieties, however, Homosassa is of indifferent quality in arid climates and has not achieved commercial importance elsewhere.

Jaffa (Florida Jaffa)
      Fruit medium-sized, globose to slightly ellipsoid or obovate; basal end commonly collared and with radial furrows; areole inconspicuous or absent; seeds comparatively few.  Well-colored under favorable conditions.  Rind medium-thick, finely pitted, and moderately pebbled.  Flesh color light orange; medium-tender, juicy; flavor good.  Stores poorly on tree, but ships rather well.  Midseason in maturity.
      Tree vigorous, upright, medium-large; foliage dense; cold-resistant; moderately productive, but with alternate bearing tendency.
      In the literature and otherwise, this variety has sometimes been confused with Shamouti or Palestine Jaffa, the principal variety of Palestine and Israel, which it resembles only slightly.  On the other hand, it somewhat resembles Joppa.  Almost certainly both Jaffa and Joppa are clones of the Palestine beledi seeding group.  Jaffa was introduced into Florida by H. S. Sanford about 1883, whether as budwood or seeds is not known, but presumably the latter.  Joppa was named about 1877 in California as a seedling from seeds obtained in Joppa, Palestine.  In this general connection, it is of interest to note that Shamouti is considered to have originated as a limb sport in a Palestinian beledi tree.
      Because of its comparatively low seed content, cold resistance, and good quality, Jaffa early became popular in Florida and attained the status of a major midseason variety.  The greater productivity and superior quality of Pineapple, however, soon caused it to lose favor, although Jaffa still remains important there and to some extent elsewhere.  For processing, however, Jaffa's susceptibility to Alternaria blossom-end infection is a further cause for its decline in popularity in Florida.

Joppa
      Fruit medium-sized, globose to slightly oblong; seeds comparatively few.  Well-colored under favorable conditions.  Rind medium-thin and slightly pebbled.  Flesh color light orange; medium-tender, juicy; flavor rich.  Midseason in maturity.
      Tree vigorous, upright, with rather stiff thornless branches and stout branchlets; precocious, and prolific.
      This variety, not to be confused with the Jaffa above, originated in 1877 from seed imported from Joppa, Palestine, by A. B. Chapman of San Gabriel, California.  It never attained commercial importance in California or in Florida, where it was early introduced, but it was popular for some decades in South Africa and still has limited importance in Texas.
      In comparison with Jaffa, the fruit averages smaller and is less oblong, the rind texture is finer, and the season of maturity is earlier.  The tree is more upright, has thicker branchlets, and is more precocious.  In general appearance, Joppa resembles Shamouti more than Jaffa.  In South Africa, it is reported (Marloth and Basson, 1955) that on rough lemon rootstock Jaffa and its seedlings exhibit budunion "crease" whereas Joppa and its derivatives do not.  Addorosa is a local synonym in South Africa.  The Fukuhara variety of Japan is considered to be a bud variation of Joppa.

Khalily White
      See under Shamouti Masry.

Khettmali (Khatmali, Hitmali)
      Fruit medium-large, round to somewhat oblong; areolar ridge usually well-developed (from which the name is derived); seeds very few.  Well-colored at maturity.  Rind medium-thin, tough, leathery; surface moderately pebbled; peels readily.  Flesh moderately firm, very juicy; flavor excellent.  Holds well on tree.  Midseason in maturity, but later than Shamouti.
      Tree vigorous and consistently productive.
      This variety appears to have originated in Lebanon, where it is highly regarded and second only in importance to Shamouti.  From the description, it is clear that Hitmali of Israel and Khettmali are identical.

Macetera
      Fruit medium-sized, subglobose to globose; apex slightly depressed; seeds few.  Rind very thin, smooth, and finely pebbled.  Color pale.  Flesh tender, juicy, and with special flavor and fragrance.  Fruit holds well on tree, but sensitive to frost.  Midseason in maturity.
      Tree robust, large-sized, and somewhat thorny.  A regular and good bearer.
      This high-quality, old Spanish variety is said to be increasing in importance, especially in Alicante Province, but its thin rind and juiciness make it a poor shipper and keeper.  It is considered excellent for processing.

Malta (Malta Common)
      Malta is a seedy, midseason orange of good color and flavor, but without distinctive characteristics, which is widely grown in the Punjab region of India and West Pakistan.  The trees are vigorous and productive.
      It is similar to and indistinguishable from beladi of the Near East and North Africa and comuna of Spain and Italy and doubtless was introduced from the Mediterranean.

Maltaise Blonde (Maltaise, Petite Jaffa, Portugaise Blonde)
      Fruit medium-large, oval; seeds very few or none.  Moderately well-colored at maturity.  Rind medium-thick, leathery; surface smooth and finely pebbled; peels easily.  Flesh moderately well-colored; juicy; flavor mild.  Does not hold well on tree, but if properly handled stores and ships well.  Midseason in maturity.
      Tree vigorous and characterized by open growth habit, thick branchlets, and large, broad leaves.  Low in productivity.
      Both the tree and fruit resemble Shamouti (Palestine Jaffa) and it is evident that they are closely related.  Markedly similar also is Shamouti Masry (Khalily White) of Egypt, which is believed to have originated as a limb sport of Shamouti.
      The Maltaise Blonde variety, of unknown origin, is of limited importance in North Africa except in Tunisia, where it is popular and grown commercially.

Maltaise Ovale (Maltese Oval, Garey's or California Mediterranean Sweet)
      Fruit medium-sized, spherical to oval; basal collar radially furrowed; seeds relatively few.  Color pale at maturity and some tendency to regreen.  Rind medium-thick; surface somewhat pebbled; peels readily.  Flesh pale-colored; moderately juicy; flavor mild.  Medium-late in maturity.
      Tree vigorous, large, spreading, and drooping; leaves long, narrow, somewhat rumpled, and of paler color than most.  Distinctive in appearance.
      This is an old Mediterranean variety of unknown origin which was introduced into California about 1870 by T. A. Garey, a pioneer citrus nurseryman of Los Angeles, and distributed under the name Mediterranean Sweet.  At about the same time, it was brought to Florida and distributed under the name Maltese Oval.  It is not the same, however, as the midseason variety introduced into Florida a few years later and distributed as Mediterranean Sweet.
      Under its California name, this variety soon became important as a midseason variety, maturing between the superior Washington navel and Valencia oranges.  With the expansion of the California industry into areas of different periods of maturity, overlapping production of these two varieties resulted.  As a consequence, Mediterranean Sweet rapidly lost favor and was replaced.  In the meantime, it was introduced into South Africa where it still retains some importance as a midseason variety, although it is no longer planted.
      Two clones are recognized in California which differ only in fruit form, one being prevailingly round and the other oblong to oval.

Marrs (Marrs Early)
      Fruit medium-large, round to slightly oblate; moderately seedy (depending on pollination).  Well-colored under favorable conditions.  Rind medium-thick, and surface smooth and finely pitted.  Flesh well-colored; juicy, lacking in acid; flavor sweet.  Holds well on tree with little loss in quality.  Earliest inlegal maturity because of low acidity, but for better juice content and quality should be left on tree somewhat later.
      Tree moderately vigorous, precocious, and prolific.  Marked tendency to bear fruit in clusters.  Smaller than most other varieties, presumably because of early and heavy bearing.
      According to Waibel (1953), this variety was found in 1927 on the place of O. F. Marrs, Donna, Texas, where it is said to have occurred as a limb sport in a group of navel orange trees obtained from California.  Although propagated to a limited extent earlier, trees were not available for commercial planting until 1940.
      Because of its early and heavy bearing and good fruit size, Marrs is currently a popular early maturing variety in Texas.  Its principal fault for processing is the low acidity of the juice.

Mediterranean Sweet
      See under Maltaise Ovale.

Mosambi (Mosambique)
      Fruit medium-large, slightly oblate to globose or broadly obovoid; areolar ring regularly shallow; moderately seedy.  Color light yellow to pale orange at maturity.  Rind medium-thick; surface moderately to roughly pebbled, and faintly striped with narrow, longitudinal grooves and ridges.  Flesh color straw-yellow; somewhat firm, juicy; flavor insipid because of very low acidity.  Early in maturity.
      This very distinctive variety is of unknown origin, but the name, of which there are numerous spellings, suggests that it was taken from Mozambique, East Africa, to India, presumably by the Portuguese.  The brown color of the chalazal spot indicates that it does not belong to the sugar orange group, as some have assumed, but that it is a low acid orange, the acidity of which is further reduced by the Indian climate and the rough lemon rootstock on which it is grown.
      Mosambi is highly popular in central India and is probably the most important orange variety of that country.  According to Gandhi (1956), it is grown principally in the Bombay Deccan where total plantings were reported to be about 20,000 acres.

Mosambique
      See under Mosambi above.

Natal
      Fruit medium-sized, globose to broadly obovoid; seeds very few.  Rind medium-thin and surface moderately pebbled.  Color pale yellowish-orange.  Flesh pale-colored; tender, fine-textured, very juicy; flavor rich at full maturity because of high acidity.  Shipping quality good.  Very late in maturity.
      Tree vigorous, large, and productive.
      Of unknown origin, this Brazilian variety is said to markedly resemble Valencia in both fruit and tree characters.

Norris
      See under Hamlin.

Nostrale Liscio
      See under Biondo Comune.

Orero
      See under Cadenera.

Parson (Parson Brown)
      Fruit medium-large, globose; base with short, radial furrows; areole indistinct; moderately seedy.  Well-colored under favorable conditions.  Rind medium-thick; surface finely pitted and moderately pebbled.  Flesh color dull orange; firm, juicy; well-flavored.  Very early in maturity, possibly the earliest.
      Tree vigorous, large, and productive.
      Parson originated as a chance seedling in the dooryard of Rev. N. L. Brown near Webster, Florida, and is said to have been planted in 1856 (Ziegler and Wolfe, 1961).  The propagation rights were purchased about 1875 by J. L. Carney, who named it Parson Brown.  Its outstanding earliness soon popularized this variety and it quickly became the leading early orange, a position held until about 1920.  Parson still remains a major variety in Florida, however, though it has never achieved prominence elsewhere, principally because of seediness.

Pera (fig. 4-7)
      Fruit medium-small, ovoid to ellipsoid; seeds very few.  Rind medium-thin; surface smooth and finely pitted.  Color light orange at maturity.  Flesh well-colored; firm, fine textured, juicy; flavor rich.  Late in maturity.  Holds well on tree without deterioration in quality, and stores and ships well.
      Tree vigorous, upright; foliage dense, with many leaves of which the petioles are unevenly winged; very productive.
      Moreira and Filha (1963) and other Brazilian horticulturists have expressed the opinion that the Pera variety is probably the same as Lamb Summer of Florida.  If so, it originated as a seedling in Volusia County sometime prior to 1897, when it was first described and named for the owner.  It never attained much importance in Florida.  Several clones are recognized of this variety in Brazil, including Perão, a light-bearing tree with fruit which is large and resembles Shamouti.  A. A. Salibe has called attention to the resemblance between Pera and the Berna variety of Spain.²
      Introduced into Brazil at an early date, Pera has long been the principal variety as well as the most important late export variety.  It constitutes nearly three-fourths of the commercial acreage in the region of Rio de Janeiro and slightly more than a third of the commercial acreage in São Paulo State.

Petite Jaffa
      See under Maltaise Blonde.

Pineapple
      Fruit medium-sized, spherical to slightly obovate; basal area sometimes depressed and radially furrowed; commonly with faint areolar ring; moderately seedy.  Well-colored (one of the best in Florida).  Rind medium-thick; surface finely pitted and slightly pebbled.  Flesh color light orange; tender, juicy; flavor rich though sweet.  Midseason in maturity.  Does not hold on tree as well as some, but excellent for processing.
      Tree moderately vigorous, medium-large, thornless, and highly productive.  More sensitive to frost than most.
      The Pineapple originated as a seedling on the place of J. B. Owens at Sparr, near Citra, Florida, and is said to have come from seed planted soon after 1860 (Ziegler and Wolfe, 1961).  It was first propagated by P. P. Bishop at Citra about 1873 under the name of Hickory and some ten years later was renamed Pineapple because of its delicate fragrance.  Its attractiveness, fine flavor, and good market reception brought about some increase in use, but it was not until after the 1894-95 freeze, which necessitated extensive replanting, that its popularity developed.  It soon became the principal midseason variety and has remained so ever since.  It is a major variety in Florida and of considerable though decreasing importance in Brazil and South Africa.  Of increasing popularity in Florida is the Queen variety, which may have originated as a Pineapple seedling.  Two virtually seedless limb sports have been found—Seedless Pineapple, discovered in 1932 on Merritt Island, Florida (U.S. Plant Patent 477), and more recently (1948) a variety named Plaquemines, which originated as a limb sport in Louisiana.  Varieties that are considered to be derivatives in South Africa include Belvedere, which is indistinguishable from Pineapple, and Gem and Letaba, both of which are less seedy and earlier in maturity.  A seedling clone that exhibits resistance to the burrowing nematode in Florida has recently been named Ridge Pineapple.

Pope (Pope Summer, Glen Summer)
      Pope is a variety so similar to Valencia that they are indistinguishable, and its origin suggests that it probably should be regarded as a selection of Valencia rather than a variety.  According to Ziegler and Wolfe (1961), it traces back to an outstanding budded tree that was found by F. W. Pope about 1916 in a 40-acre planting of the Pineapple variety near Lakeland, Florida.  It was so late in maturity and held the fruit so well without loss in quality that Pope undertook its commercial propagation in 1935 and had the name trademarked in 1938.  Since 1945 its propagation and promotion have been conducted by Pope Summer Orange Nursery, Ltd., though the same variety is reported (Ziegler and Wolfe, 1961) to be propagated by the Glen St. Mary Nurseries Company under the name Glen Summer.  It has been planted to a considerable extent in the Indian River district of Florida.

Portugaise Blonde
      See under Maltaise Blonde.

Precoce des Canaries
      See under Cadenera.

Precoce de Valence
      See under Cadenera.

Premier
      Fruit medium-small, globose; seeds relatively few.  Rind medium-thick and surface moderately coarse.  Flesh very juicy and flavor good.  Early midseason in maturity.
      Tree moderately vigorous, of irregular, upright growth habit; medium-sized; very productive.
      Of unknown parentage, Premier is a selection of the Joppa type introduced about 1935 by the late Professor H. Clark Powell, of the University of Pretoria, from the Mazoe Citrus Estates, Umtali, Southern Rhodesia.  Montrose Premier is indistinguishable and apparently represents a clonal selection.  The so-called Orange Premier is an entirely unrelated clone of the Jaffa type that is subject to the budunion crease disease and should be discarded.  Premier has proven to be popular and is currently the most important midseason variety in the Lowveld areas of Transvaal, South Africa.  It also is grown extensively in Southern Rhodesia.

Queen
      The Queen was originally named King, but later the name was changed to avoid confusion with the old King mandarin variety.  This is a midseason variety with fruit much like the Pineapple orange.  It is less pronounced reddish-orange in color, higher in soluble solids and hence richer in flavor, somewhat less seedy, and holds better on the tree.
      The tree is more vigorous than Pineapple, equally productive, and somewhat more resistant to cold.
      According to Ziegler and Wolfe (1961), this variety originated as a seedling in an old orchard on Lake Hancock, near Bartow, Florida, and came to notice prior to 1900 at which time budwood was obtained by a Mr. Walters from a Mr. King, a son-in-law of the owner.  It was used to propagate trees for the Perrin and Thompson Groves near Winter Haven, the owners of which gave it the name King.  Its commercialization was undertaken by the Lake Garfield Nurseries of Bartow about 1915 under the present name.  For some decades it did not receive much attention, but its popularity has increased appreciably in recent years.

Salustiana (Salus) (fig. 4-8)
      Fruit medium-large, subglobose to spherical; basal cavity shallow with faint radial furrows; apex depressed; areolar ring small but well-marked in many cases; virtually seedless.  Unusually well-colored at maturity.  Rind medium-thick and surface moderately pebbled.  Flesh melting, juicy; flavor rich and sweet.  Fruit said to hold especially well on tree without much loss of quality.  Early in maturity (earliest of the Spanish varieties).
      Tree vigorous, somewhat upright, medium-large, and productive.
      This comparatively new Spanish variety is believed to have originated as a limb sport on a comuna tree in the garden of a convent.  It was called to the attention of Don Salustiano Pallas of nearby Enova, Valencia, and propagated and introduced by him about 1950 (Gonzalez-Sicilia, 1963).  Because of its early maturity, seedlessness, and quality, it is regarded as highly promising and has been planted to a considerable extent in Spain in recent years and somewhat in Algeria and Morocco.
      According to Chapot and Huet (1963), who have reported on the characteristics of this variety in North Africa, both tree and fruit are indistinguishable from Cadenera, except that the latter is somewhat flatter in form.  Salustiana is much earlier in maturity, however.

Sathgudi
      Fruit medium to large, globose; moderately seedy.  Color greenish-yellow to pale orange at maturity.  Rind medium-thick, tough, leathery; surface finely pitted and moderately pebbled; peels readily.  Carpellary membranes thick and tough; flesh orange-colored; juicy; flavor fair (sweet with some acid).  Midseason in maturity insofar as can be determined.
      Tree vigorous and moderately productive.  Commonly seed-propagated.
      The origin of Sathgudi is unknown, but probably relates to a village or community.  However, one of its local names in southeast India suggests that it may have come from Batavia, Indonesia.  For many years it has been the principal variety in southern India.

Seleta (Selecta, Siletta)
      Fruit medium-sized, subglobose to spherical; basal area sometimes with radiating furrows; apex rounded or slightly flattened; areole usually distinct; seeds few.  Rind medium-thick; surface smooth to slightly pebbled; color light orange.  Tendency to color in advance of maturity, while still acid.  Flesh juicy; flavor somewhat acid until full maturity, when it becomes sprightly and readily acceptable.  Fruit does not hold well on tree after maturity, dropping freely.  Late midseason in maturity though coloring early.
      Tree moderately vigorous, medium-sized, and regularly productive.  A tendency to give rise to budvariations has been noted in California (Webber, 1943, p. 516) and Australia.³
      The origin of Seleta is unknown, but it seems likely that it is an old Portuguese variety, for in 1925 it was listed among those currently grown there (Bobone, 1938) and the synonym employed, Lusitana, referred to the ancient Roman provincial name for Portugal.  Presumably taken to Brazil at an early date, it is the variety from which the Bahia or Washington navel orange is supposed to have originated (Dorsett, Shamel, and Popenoe, 1917), although to the writer this seems improbable.  According to Moreira and Filha (1963), it is still of commercial importance in Brazil, where several clonal selections are currently popular—Abacaxi, Amarela, Branca, Itaborai, and Vermelha.  It seems likely that this variety is the Siletta of Australia as the Sydney Gazette of April 22, 1824 (Bowman, 1955) lists Celeta and Bahia oranges among recently introduced citrus varieties.  It early achieved commercial importance in Australia, which continued until about 1920.  Since that time it has been infrequently planted and only for juice purposes.
      Two clones have long been recognized in Australia—White Siletta, which corresponds to the description given here, and Red Siletta, so-named because of its deeper color.  The Red Siletta is presumably of local though unknown origin.  The first-mentioned clone is that which achieved principal importance.  The fruit of the latter is coarser in rind texture and somewhat lower in quality; the tree is more vigorous and larger.

Shamouti (Chamouti, Palestine Jaffa, Jaffa, Jaffaoui, Iaffaoui). (fig. 4-9)
      Fruit medium-large to large, oval to ellipsoid; basal end slightly flattened or depressed with narrow and low collar or shoulder, commonly with short radial furrows; apical end evenly rounded; areolar ring usually present but faint.  Seedless or nearly so and well-colored under favorable conditions.  Rind thick, tough, and leathery; surface finely pitted but relatively smooth; inconspicuous oil glands.  Flesh color light orange; firm, tender, juicy; fragrant and pleasantly sweet-flavored.  Fruit peels and segments separate readily.  Ships and stores unusually well, but does not process well.  Midseason in maturity.
      Tree moderately vigorous, distinctive in appearance, upright in growth habit, with thick, thornless branchlets; leaves large and broad, with petioles which are small and narrowly winged.  OnPalestine sweet lime rootstock, tree is somewhat dwarfed, probably because of xyloporosis infection, but isregular and highly productive, whereas tree islarger on sour orange but less productive because of pronounced alternation.
      While Shamouti, of which there are various other spellings, is the preferred name for this distinctive and highly important variety, it is so well and favorably known in Europe under the name Jaffa that it is now impracticable, as well as undesirable, to undertake to change this usage.  There is another, quite different variety of the same name and parentage, however, frequently called Florida Jaffa to distinguish between them (see Jaffa).
      Like the navel oranges in general, the Shamouti tree is sensitive to heat and aridity during the bloom and hence restricted in range of climatic adaptation.  Thus, in very hot, arid regions production is low and the fruits are undesirably large and coarse.  Shamouti is clearly not adapted to hot desert or semitropical climates.  For reasons that are not clear, probably relating to both climate and rootstock, the commercial culture of this variety is restricted to climatically favored portions of the eastern end of the Mediterranean basin.
      According to Oppenheim (1927, 1929), Shamouti originated some time prior to 1844 in an orchard near Jaffa, Palestine (now Israel), presumably as a limb sport in a tree of the local or beledi variety (see also under Jaffa).  Its qualities were so outstanding that within a few decades it became the leading variety in Palestine and has maintained this position ever since.  It spread to nearby countries and attained importance, notably in Lebanon, Turkey, and Cyprus.  It was early exported to Europe, principally England, where it soon established a reputation for its size, quality, and seedlessness.  Its distinctive shape provided a natural trademark.  Currently, Shamouti is by far the principal variety of the Near East and one of the major varieties of the world.  In addition to the countries already mentioned, it is the leading variety in Syria and is grown to some extent in Greece and Egypt.  The 1965 production of this variety was estimated at not less than 20 million boxes.
      Although efforts were made early to establish this highly reputed variety in both California and Florida, the seed introduced apparently came from fruits of the seedy parent variety rather than the almost seedless Shamouti and gave rise to the Florida Jaffa and Joppa varieties (see Jaffa and Joppa).  This fact was not realized for many years, and it was not until about 1920 that the true Palestine Jaffa (Shamouti) was introduced.  Thus far, it has not compared favorably in quality and productivity with other varieties.
      The evidence indicates that the Shamouti clone is highly unstable and prone to the occurrence of limb sports.  Thus, Oppenheim (1927, 1929) and Chapot (1964c) report numerous instances of Shamouti trees containing branches that produce round, seedy fruits typical of beledi, and a few cases have been reported of beledi trees with Shamouti-like limb sports.  Chapot (1954, 1955b) reports the existence of four varieties in Lebanon, the names of which clearly suggest the likelihood of Shamouti origin.  They are Shamouti or Iaffaoui Beledi, a seedy Shamouti; Shamouti or Iaffaoui Maouardi, a seedless blood Shamouti; Maouardi Beledi, a seedy, blood Shamouti; and Shamouti or Iaffaoui Moghrabi or Meski, an acidless, seedy Shamouti.  Other varieties which markedly resemble Shamouti and are known to have originated from it include Kinariti or Kinnereth (Early Shamouti) and the pink-fleshed Sarah of Israel and Shamouti Masry (Egyptian Shamouti or Khalily White).  (See Shamouti Masry, below.) Finally, it should be noted that Maltaise Blonde of North Africa, sometimes called Petite Jaffa, and Barile of Italy closely resemble Shamouti though their fruit is somewhat smaller (see Maltaise Blonde).

Shamouti Masry (Khalily White, Egyptian Shamouti)
      Fruit medium-large, ellipsoid to oval; seeds few or none.  Color orange to deep orange.  Rind medium-thick; surface finely pitted and relatively smooth; peels readily.  Flesh well-colored; juicy; flavor rich and sweet.  Midseason in maturity.  Indistinguishable from Shamouti.
      Tree moderately vigorous; leaves large; Shamouti-like in appearance; productive.
      This variety is said to have originated in the orchard of Moustafa Khalili in Kalioubiyah Province, Egypt; whether it occurred as a seedling or limb sport is not reported.  It is preferred to Shamouti because the tree is more productive and the fruit somewhat smaller and of finer texture.  From descriptions it is evident that this variety and Maltaise Blonde or Petite Jaffa of North Africa are very much alike.

Tomango
      See under Pigmented Oranges.

Valence san Pepins
      See under Cadenera.

Valencia (Valencia Late, Hart Late, Hart's Tardiff) (fig. 4-10)
      Fruit medium-large, oblong to spherical; areole ring faint or lacking; seeds few or none.  Well-colored at maturity, but regreens thereafter under certain conditions.  Rind medium-thick, tough, and leathery; surface smooth to faintly pebbled.  Juice abundant and flavor good but commonly somewhat acid.  Fruit holds exceptionally well on tree with little deterioration in quality and ships and stores well.Excellent for processing.  Latest maturing of all commercial varieties.
      Tree vigorous, somewhat upright, large and prolific, but with alternate-bearing tendency.  Very wide range of adaptation.
      This variety should not be confused with the Spanish Valencia Temprana and various seedling clones grown in the region of Valencia, Spain.
      The total heat requirement for maturity of the Valencia orange is so high that only in the hottest regions is it satisfied prior to the succeeding bloom.  In the United States, this usually occurs in Florida, the Lower Rio Grande Valley of Texas, and the low elevation desert areas of Arizona and California, where legal maturity is normally attained in January or February, though the fruit may be stored on the trees for several months thereafter, extending into or through the succeeding period of bloom.  In regions of lower total heat, however, maturity is later and overlaps the bloom, sometimes by several months.  As a consequence, in most regions where this variety is grown the trees normally carry two crops—the old, which is ripe or reasonably close to maturity, and the new, at any stage of bloom to half-grown or thereabout.  In regions of mild winters and moderately low total heat during the growing season, such as the coastal belt of southern California, Valencia becomes a summer-ripening fruit, but with crops that alternate appreciably in amount and somewhat in fruit size.  Because the fruit stores remarkably well on the trees without much dropping and little loss in quality, it is practicable in this cool, equable region to extend the harvesting season through the summer into fall and to ship tree-ripened Valencia oranges as late as October or early November—17 or 18 months from the time of bloom.
      Presumably associated with its very high total heat requirement and the relatively high acid content of the fruit is the fact that the Valencia orange exhibits the widest range of climatic adaptation of any orange variety of commercial importance.  It is suitable for the heat-deficient, mild, subtropical climate of coastal southern California, the hot, low elevation desert regions of California and Arizona, the humid, semitropical climate of Florida, and tropical climates in general.
      As might be expected, Valencia is therefore much the most important variety of the common sweet orange group and seems likely to remain so.  It is of major importance in both Florida and California and currently accounts for about half the total orange production of the United States.  It is also of major importance in South Africa, Australia, and Mexico and of considerable importance in Israel, Algeria, Morocco, and Brazil.  In the 1965-66 season, production was 48.9 million boxes (90-1b) in Florida and 19.3 million boxes (75-1b) in California and Arizona.  Including production elsewhere, a conservative estimate of the current world production of this variety would appear to be not less than 100 million 70-pound box equivalents.  In Florida, approximately 80 per cent of the crop is processed for juice products, whereas in California about two-thirds is shipped fresh.
      The common assumption that this variety is of Spanish origin is not supported by the evidence.  While varieties of similar appearance exist in the Valencia region of Spain and elsewhere, none is characterized by the lateness of maturity of Valencia.  Berna, which approaches it in late maturity, is altogether different in other respects.  Valencia Temprana, the only Spanish variety with the name Valencia, is an early ripening fruit of smaller size and flatter form that is no longer propagated (Gonzalez-Sicilia, 1963, pp. 198 and 201).  Moreover, Gonzalez-Sicilia states (1963, p. 211) that the Valencia variety originated in the United States and was introduced into Spain by the Estación Naranjera de Levante at Burjasot, near Valencia.
      The English nurseryman, Thomas Rivers of Sawbridgeworth, imported this variety from the Azores Islands and catalogued it in 1865 under the name Excelsior (Coit, 1915).  About 1870, he provided trees to S. B. Parsons, a Long Island Nurseryman, and in 1876 he sent trees to A. B. Chapman of San Gabriel, California.  In the meantime, Parsons sold trees to E. H. Hart of Federal Point, Florida, where in 1877 the variety received the name Hart's Tardiff.  According to Webber (1943, p. 523), the trees received by Chapman were unlabeled and included several varieties, one of which proved to be late maturing and was provisionally called Rivers Late.  A few years later Chapman changed the name to Valencia Late at the suggestion of a Spanish visitor who pronounced it similar to a late-maturing variety in the region of Valencia.  It was not until several decades later that comparisons in California established the fact that these two indistinguishable varieties were identical and much later that this fact received recognition in Florida.
      While this variety can be traced back to the Azores, it seems unlikely that it originated there and probable that it came from Portugal.  That likelihood has been greatly strengthened by the recent discovery there of an old variety that is indistinguishable from Valencia, which has been named Don João (Galvão, 1943; Chapot, 1963c).
      Byron O. Clark (1916) appears to have been the nurseryman most responsible for the popularization of the Valencia orange inCalifornia.  The first commercial orchard was established near Placentia about 1880 when R. H. Gilman converted a young planting of five acres to the new variety by top-budding.  The first carload of Valencia oranges shipped to eastern markets, however, is reported to have been sent in 1877 by J. R. Dobbins of San Gabriel.
      Other varieties that are indistinguishable from Valencia include Lue Gim Gong and Pope of Florida, Natal of Brazil, Calderon of Argentina, and Harward of New Zealand.  Two of these—Lue Gim Gong and Harward—are known to have originated as Valencia seedlings and doubtless represent nucellar selections of that variety.
      As would be expected in a clonal variety of such extensive propagation and wide distribution, bud variation of Valencia has given rise to a number of mutant varieties, among which are Armstrong and Perry of California, Muden of South Africa, and Seedless Valencia of Australia.  Ksiri, a seedless mutation, has recently been reported in Morocco (Merle, Chapot and Huet, 1964).
      For some decades past, clonal selections have been widely used in both Australia and California and presumably to some extent elsewhere.  Those currently most popular in Australia are reported to be Berri, Lord Howe, and Norton or Chaffee.  These and St. Ives, a selection used in coastal New South Wales, all trace back to outstanding trees propagated from introductions made by the Chaffey Brothers of California in the early 1890's for use in their nursery operations at Mildura, Victoria.  Another selection is Chapman, which came direct from California.  Levitt reports that when grown side by side at the Narara Horticultural Research Station, New South Wales, these Australian clonal selections have been indistinguishable and without significant differences in performance or behavior.⁴  Under the arid conditions of the lower Murray River Valley, however, they hold their color and juice qualities later into the summer and fall than other selections.
      The principal five old budline clonal selections in California have been Azusa, Randall, Hardison, San Marino, and Sespe.  The latter three closely trace back to the original tree at San Gabriel and are not more than two or three bud generations removed from it.  Azusa is undoubtedly not far removed from the original tree, but the parent tree is unknown.  Randall is known to have been introduced from Florida in 1903 as Hart's Tardiff, the name given to this variety there in 1877.  Distinctive differences between these California clonal selections are not discernible.
      In recent years, most of the trees planted in California have been of nucellar budlines, which are virus-free, more vigorous, and commonly more productive.  Currently the most popular of these are Cutter, Frost, and Olinda.  The latter two are indistinguishable, but Cutter appears to be somewhat more vigorous, presumably because of its more recent origin.  Campbell is also popular and outstandingly vigorous.  In the opinion of the writer, however, the parent clone differs from Valencia and constitutes a separate variety.

Verna
      See under Berna.

Vicieda (Viciedo)
      Fruit medium-small, short-oval; base with shallow radial furrows; occasional areolar ring; moderately seedy.  Color light orange.  Rind medium-thin and finely pebbled.  Flesh color pale; texture somewhat fibrous; not very juicy; well flavored.  Early midseason in maturity.
      Tree medium-large and moderately productive, but with marked tendency to alternate bearing.
      This old Spanish variety, which is also grown to some extent in Morocco and Algeria, is declining in importance in favor of superior varieties.
      An unnamed improved selection of Vicieda is recognized (Gonzalez-Sicilia, 1963) in which the basal radial furrows are lacking, the rind is thinner, smoother, and better colored, the flesh juicier, and the seed content lower.  Indeed, there is reason for the conclusion that Vicieda consists of a group of clones, some of which are much better than others.

     Minor Common Orange Varieties.—Common orange varieties of lesser commercial importance or more local interest than those discussed in the preceding subsection are presented below.

Arancio Barile
      See under Barile.

Armstrong (Armstrong Seedless Valencia, Mohn)
      Presumably a bud variation of Valencia, Armstrong is a Californian variety indistinguishable from the parent except that the fruit is virtually seedless (very occasionally a seed).  The parent budded tree was found about 1928 in the orchard of Pearl C. Mohn at Anaheim, California.  The new variety was patented in 1935 (Patent No. 124) and was introduced by the Armstrong Nurseries of Ontario in 1939.  It has not achieved much importance, presumably because the parent variety is so nearly seedless (none to five or six seeds).

Aziza
      This Moroccan variety is a beledi selection or unknown origin that was formerly of local importance and has now been replaced largely with better varieties.  The fruit matures in midseason and is nearly seedless, medium-small, and oblong to oval, with a medium-thick, tightly adherent rind.  The flesh is tender, melting, and of good flavor.  The tree is moderately vigorous, somewhat upright, and possesses an alternate bearing tendency.

Bailidge
      The tree of the Bailidge variety is vigorous and productive, yielding an attractive, medium-large, very few-seeded, midseason-ripening fruit.  As in the case of Clanor, this South African variety also traces back to old, layered, seedling orange trees, in this instance three adjoining and indistinguishable trees on the property of Bailey and Cumberlidge near Rustenburg in western Transvaal.  The date of its selection and the person responsible are unknown.  Late to come into bearing and mediocre in quality.  Bailidge is no longer popular except in the eastern Cape Province region.

Barile (Arancio Barile)
      This old Italian variety is of unknown origin and was never important except in the Adrano district, where it has been little planted for many years.  Barile is a few-seeded, medium-sized, late midseason fruit that is distinctive in form in that it is oblong-oval with a furrowed neck or collar.  The rind is of medium thickness, moderately pebbled, and bright orange in color.  The flesh is firm and of agreeable flavor.  Of medium vigor and size, the tree is not very productive.  Chapot reports that this variety markedly resembles the Shamouti of Israel and is closely related, if not identical.⁵

Best (Best Seedless)
      Best is one of a number of varieties of local origin or selection that are considered promising in New Zealand.  Such varieties currently comprise about 20 per cent of the sweet orange acreage in that country.  Best is a virtually seedless fruit of early midseason maturity and is characterized by the frequent presence of a navel, juicy flesh, and rich flavor.  The tree is vigorous and productive.  The variety originated as a rootstock seedling of unknown parentage on the property of a Mr. Best at Avondale, Auckland.

Bibile (Bibile Seedless)
      A variety with seedless fruit of good rind texture and quality, Bibile originated as a seedling in the Bibile district of Ceylon.  It was found by A. V. Richards, government horticulturist, and named and introduced in 1949 (Richards, 1949).

Blanche de Teneriffe
      See under Tenerife.

Boone (Boone's Early, Giddings)
      A very early ripening, light-colored, moderately seedy fruit of medium size and good flavor, Boone was popular in the early decades of the Florida industry but was soon superseded by Parson and Hamlin.  According to Webber (1943), the fruit is highly variable, poorly colored, and drops badly following maturity.  The variety is said to have originated as a seedling selected by a Mr. Giddings near Webster and was first propagated by David Collins of that locality under the name Giddings.  It was promoted under its present name in 1889 by C. A. Boone of Orlando, but has not been planted for many years.

Branca
      See under Prata.

Burton (Helen Burton)
      This South African variety produces a virtually seedless, high quality, medium-sized fruit of midseason maturity.  The tree is vigorous, upright-growing, large, densely foliated, and productive.  Burton originated as a seedling of Cape Seedling parentage in a small planting originally owned by Mrs. Helen Burton at Clanwilliam, western Cape Province.  The selection was made in 1954 by G. Joubert, field officer at Citrusdal for the South African Cooperative Citrus Exchange.  This new variety is considered promising and a few young plantings currently exist in western Cape Province.

Butler
      Fruit medium-large, oblong to ellipsoid; color light orange; moderately seedy.  Flesh juicy and well flavored.  Early midseason in maturity.
      Tree vigorous, large, and productive.
      This Arizona variety apparently originated from seedlings imported from Florida about 1895 and was found about 1915 in the orchard of Robert Butler near Phoenix.  It was first propagated about 1925 and is currently the most popular early season variety in central Arizona.

Cadena Punchosa
      A moderately seedy, midseason Spanish variety that much resembles Cadenera, Cadena Punchosa is inferior in that the fruit is much seedier.  In addition, Gonzalez-Sicilia (1963) reports that the juice content is lower, the flavor less rich, and the season of maturity a little later.  Chapot reports that in Morocco these differences are not evident.  Cadena Punchosa has largely been replaced with less seedy varieties and is no longer planted.⁶

Calderon
      This late-ripening Argentinian variety so closely resembles Valencia that the two are virtually indistinguishable.  The fruit is medium-sized, well-colored, and has few seeds.  The tree is vigorous, large, round-topped, and productive.  A comparatively new variety, Calderon is reported to have originated as a chance seedling that came to notice in a seedling orchard near Resistencia, Chaco Province.  It is rapidly increasing in popularity and during recent years has been planted extensively in Misiones Province and to some extent in the Concordia district of Entre Ríos Province.

Campbell
      This Californian variety is commonly and, in the opinion of the writer, erroneously called Campbell Valencia.  The fruit is indistinguishable from Valencia, but the tree exhibits certain consistent, discernible differences in vigor and behavior in comparison with Valencia.  In trials of the two parent clones and of nucellar clonal budlines of comparable age, the trees of Campbell have consistently been more vigorous, thornier, larger, broader-topped, and slower to come into bearing than Valencia.  The fruit has also been slightly lower in juice content than Valencia in the coastal region and has exhibited a greater tendency to regreen in the interior districts (Lombard, 1663).  Moreover, in a trial at Santa Paula, Campbell is reported to have shown a higher, though small, percentage of fruits that were creased or of a chimeric nature.  These differences, however, might possibly relate to infection by the stubborn virus.
      The parent tree came to light about 1942 in the Early Campbell orchard near Santa Ana, which was planted in 1871 (Bitters, Batchelor, and Foote, 1956).  Almost certainly it was a seedling, for budded trees were little used at that time, which was five years before the introduction of the Valencia variety in California.  The possibility that the orchard could later have been topbudded to Valencia is remote, for trees propagated from roots of this tree some years ago have shown no differences whatever from those propagated from the top.  And, finally, there are the differences noted in the trials.
      During recent decades Campbell has been planted considerably in California.  More recently, the Campbell nucellar budline has achieved popularity.  This seedling is indistinguishable from Campbell, but is more vigorous, thornier, and considered to be of nucellar origin.  It was derived some time prior to 1942 by H. S. Fawcett at the Citrus Research Center, Riverside, California.  It should probably be called Fawcett Campbell.

Capuchina (Capucin)
      This Spanish variety produces a medium-small, oblong to oval fruit of low seed content, very sweet flavor, and midseason maturity.  Capuchina is still of local importance, primarily in the Orihuela district of Alicante Province, but it is no longer planted.

Casa Grande (Oasis)
      Casa Grande is an early ripening, highly productive Arizona variety, the fruit of which is medium-small and moderately seedy.  The tree is vigorous, upright, somewhat thorny, and yields heavily.
      The variety originated as a dooryard seedling in Casa Grande, attracted attention about 1925, and was first propagated by C. J. Wood, who made a commercial planting in the Salt River Valley in 1930.  A few small plantings have been made in recent years, but this variety seems unlikely to become important.

Conner (Conner's Seedless)
      The Conner is a medium-small, nearly seedless, midseason fruit.  This variety, which is of exceptional tree vigor, originated as a seedling in the old orchard planted about 1879 near Glenwood, Florida, from which the Hamlin variety came to light.  Webber (1943) considers the Carlton variety identical to Conner.  Conner was popular for some decades and old orchards still remain.

Croc (Croc 25)
      This South African variety has a very early ripening, moderately seedy fruit of good flavor, and is of interest primarily because it originated as a limbsport in a Washington navel orange tree.  Though seedier, it bears considerable resemblance to the Marrs variety of Texas, which is of similar origin.  Croc came to light comparatively recently in one of the orchards of the Crocodile Valley Citrus Estates near Nelspruit, eastern Transvaal, where the only commercial planting occurs.

Cutter Valencia (Cutter Nucellar Valencia)
      This California nucellar seedling was derived about 1935 by H. S. Fawcett of the Citrus Research Center, Riverside, from an outstanding old Valencia tree in the J. C. Cutter orchard at Riverside.  This seedling budline was released in 1957 and is currently popular.  Cutter is exceptionally vigorous and thorny and somewhat slow to come into bearing.

Dacre
      Dacre is a local midseason variety in New Zealand.  The fruit is medium to medium-small, low in seed content, juicy, and of good flavor.  The tree is vigorous and productive.
      The variety originated as a seedling of unknown parentage on the property of a Mr. Dacre in the Bay-of-Islands district of northern New Zealand.

Delicious (Partin Delicious)
      An early maturing fruit with considerable resemblance to Parson, Delicious is smoother in rind texture, deeper in flesh color, and contains fewer seeds.  The fruit also holds better on the tree without dropping or loss in quality.  The tree is vigorous, unusually upright, and productive.  According to Ziegler and Wolfe (1961), this Florida variety traces back to a seedling of unknown origin that came to the attention of Clay S. Partin about 1900 and has been propagated ever since for use in the Partin family holdings.  It was introduced commercially in 1958 by the Lilian S. Lee Nurseries of St. Cloud.  It is considered to be promising.

Delta
      This South African variety produces a seedless fruit of high quality that resembles the Valencia but matures somewhat earlier.  The tree is vigorous and productive.  Delta originated as a dooryard seedling.  It is thought to be of Valencia parentage and was found in 1952 by A. Smith, Government Entomologist, at Rustenburg, western Transvaal.  It is considered to be promising and has already been planted to some extent.

Diller
      Fruit small to medium, oblong to slightly ellipsoid; seeds comparatively few.  Color bright orange.  Rind medium-thick and moderately pebbled.  Flesh well-colored, juicy; flavor good.  Early in maturity.
      Tree moderately vigorous; short, thick, upright-growing branchlets and leaves; productive under desert conditions.  Said to be above average in cold tolerance.
      This Arizona variety originated as a seedling of Florida origin in the orchard of Daniel Diller near Phoenix and was selected in 1910 and introduced about 1920.  It soon became popular as an early variety in the Salt River Valley, where the 1965 planting was said to be about 1,000 acres.

Diva
      The fruit of this late-ripening Brazilian variety is medium-sized, firm but juicy, of good flavor, and contains very few seeds.  It is said to ship and keep well.  The tree is of medium vigor and size, upright in growth, and only moderately productive.  Of unknown origin and limited importance, Diva is considered to be promising.

Don João
      This is a very late-ripening Portuguese variety that came to light in 1943 in the Don João quinta (orchard) near Beja (Galvão, 1943).  It is so similar to Valencia that Eng. Bento Nascimento, director of an agricultural research station at Tavira in the important Algarve citrus region, lists it in a recent communication as a synonym for Valencia Late.
      Don João traces back to two very old trees, the sole remaining survivors in 1943 of a larger planting.  The fruit of these trees was very late in maturing and held well on the trees through summer without loss of quality.  The writer recently visited this orchard and found only one tree remaining.  The tree is thought to be not less than eighty years old and may be older, although it has been neglected for many years, severely pruned, and does not look that age.
      The writer found young, bearing Don João trees alongside Valencia at both the Tavira and Setúbal citrus research stations to be indistinguishable.  He considers the possibility good that they are the same, since contrary to popular belief the evidence indicates that Valencia is likewise of Portuguese origin or introduction (see Valencia).  Don João has been much planted in Portugal in recent years and on a small scale in Morocco (Chapot, 1963e).

Du Roi
      Du Roi produces a medium-small, moderately seedy fruit and came into prominence in the early period of the Florida citrus industry, primarily because of its medium-late maturity.  It was soon replaced by Valencia, however.  Widely distributed to other countries, it achieved commercial importance principally in South Africa where old orchards still remain, though it has not been planted for some decades.
      The origin and history of Du Roi are obscure, but according to Webber (1943) it was probably introduced into Florida from the Mediterranean basin by the Thomas Rivers Nursery of Sawbridgeworth, England.

Early Shamouti
      See under Kinarti.

Enterprise (Enterprise Seedless)
      Enterprise produces a medium-small, commercially seedless, early ripening fruit.  The variety was prominent in the early period of the Florida industry.  It is still sparingly planted in Brazil, but has largely been replaced by Hamlin.
      Enterprise originated as a seedling in an orchard at Glenwood, Florida, near De Land.  It was recognized as promising about 1880 and named for the nearby town of Enterprise.  In arid climates, the fruit is too small to compete with other and better varieties.

Escalon
      This Mexican variety produces a seedy, oblong fruit of midseason maturity that has a smooth rind and good color and flavor.  Escalon is believed to have originated as a seedling selection in Jalisco State, where it is currently the most popular variety.

Folha Murcha
      This is a late-ripening Brazilian variety with fruit that markedly resembles the Valencia.
      The tree is moderately vigorous, upright in growth, with stout branchlets and large dark green leaves that give it some resemblance to Shamouti.  The leaves, however, are rolled and appear to be wilted, from which the name (withered leaf) is derived.  Folha Murcha is very productive.  Of unknown origin and presumably a bud variation, this unusual variety is currently of minor importance but is considered promising.

Frost Valencia (Frost Nucellar Valencia)
      Frost Valencia is a nucellar seedling derived about 1915 by H. B. Frost of the Citrus Research Center, Riverside, and released in 1952.  Exceptionally vigorous and productive, it is the oldest of the California nucellar budline selections and currently the most popular.

Fukuhara
      This Japanese variety produces a moderately late-maturing, occasionally navelled fruit of medium size, deep color, high juice content, and rich, sprightly flavor (sugar and acid both high), with few seeds.  The tree is vigorous, productive, and more cold-tolerant than other late ripening varieties.
      Fukuhara was found by S. Fukuhara in Chiba Prefecture in 1922, but it was not until six years later that K. Noro called attention to its desirable features.  While its parentage is unknown, it is believed to be a bud variation of the Joppa variety.  It is grown to some extent on Kyushu Island and in Wakayama Prefecture of Honshu Island, where it is recommended as a late-maturing variety.

Fuya Menuda (Hoja Pequeña, Oranger des Baleares, Oranger de Soller)
      An interesting Spanish variety, apparently originating in the Balearic Islands, Fuya Menuda is highly ornamental because all parts of the plant—tree, leaves, and fruit—are markedly reduced in size.  It constitutes the only truly dwarf sweet orange variety known to the writer.

Giddings
      See under Boone.

Harward Late (Harward Valencia)
      This New Zealand variety is a seedling of Valencia with fruit that is indistinguishable from its parent.  The tree is vigorous, large, and productive, and since its overall performance is thought to be superior it seems likely to replace Valencia in New Zealand.
      Harward Late originated at Tauranga and probably represents a clonal budline of nucellar seedling origin.  The name Harward Valencia would therefore seem more appropriate.

Hoja Pequeña
      See under Fuya Menuda.

Johnstone Valencia
      This South African clonal selection is an outstanding Valencia tree on the place of Mrs. J. Johnstone at Zuurplaats, near Rustenburg, western Transvaal.  Reported to be the most popular South African selection currently in use, it scored highest in the Citrus and Subtropical Fruit Research Institute trial held at Alkmaar (Marloth, Basson, and Bredell, 1964).

Jordan
      This Arizona variety resembles Butler but the fruit is less seedy.  It was discovered about 1925 in the orchard of Mrs. S. E. Jordan near Phoenix and was introduced about 1930.  Of unknown parentage, it is thought to be either a seedling or bud variation of Butler and is finding favor as a substitute for it.

Kinarti (Kinnereth, Early Shamouti)
      The Kinarti of Israel produces a Shamouti-like but smaller, smoother-skinned, and earlier-ripening fruit.  The variety was found a few years ago as a limb sport of Shamouti in a small orchard in Kinnereth Colony near Lake Tiberias.  Although of good quality, it bears poorly and has not achieved commercial importance.

Kinnereth
      See Kinarti above.

Ksiri
      This Moroccan variety is considered to be a bud mutation of Valencia (Merle, Chapot, and Huet, 1964), but the fruit is smaller and much flatter (subglobose to broadly oblate), the rind is smoother and more tightly adherent with a tendency toward persistence of the style, and seeds are completely lacking.  The flesh is juicier and both sugars and acids are somewhat higher.  The maturity season is fully as late as Valencia, possibly somewhat later.  The fruit holds well on the tree, which is less upright and vigorous than Valencia but with larger, broader, and more round-pointed leaves.
      Ksiri is a comparatively new variety that was found as a single tree in a young, bearing Valencia orchard in the region of Mechra Bel Ksiri.

Lamb (Lamb's Summer)
      Lamb is a very late-maturing Florida variety.  The fruit is medium-small, ovoid to ellipsoid, contains very few seeds, and holds well on the tree with little loss in quality.  According to Webber (1943), this old variety originated as a seedling in the nursery of a Mr. Lamb in Volusia County and was named by a neighbor, E. O. Painter, who recognized its distinctive characteristics.  It did not attain much importance and has not been planted for many years.
      It is of interest to note, however, that Moreira and Filha (1963) and other Brazilian specialists have recently expressed the opinion that Pera, currently the principal variety there, is probably the same as Lamb.

Late Shamouti
      This late-ripening, Shamouti-like variety originated in Israel as a bud sport of Shamouti.  Its history is not available to the writer.  Because of its late maturity (approximately the same as Valencia), it is considered to be promising and is now under commercial trial in Israel.

Letaba (Letaba Early)
      The South African Letaba variety produces a richly flavored, moderately seedy (as compared with Pineapple), medium-large fruit of early midseason maturity.  It is included here primarily because of its commercial importance in the extensive plantings of the Letaba Estates in northeastern Transvaal and because it is superior to Pineapple in important respects.  Its origin is unknown, but a resemblance to Pineapple suggests that it is a selection of that variety.

Lue Gim Gong
      This so-called Florida variety in all respects is indistinguishable from Valencia.  In all probability, it represents a nucellar clonal budline of that variety and hence should be called Lue Gim Gong Valencia.
      According to Ziegler and Wolfe (1961), at the time of its introduction in 1912 it was claimed to be a hybrid of Valencia and Mediterranean Sweet, made at De Land in 1886 by a Chinese gardener of that name.  It was said to mature later than Valencia and hold better on the tree, neither of which claims have proven to be true.  It is still planted to a limited extent in Florida, however.

Mazizi
      See under Yousef Solimon.

Mediterranean Sweet (Sanford's or Florida Mediterranean Sweet)
      This variety has medium-large, well-colored fruit of low seed content and late midseason maturity.  It was widely planted in Florida in the early period of the citrus industry and some old orchards still exist.  According to Webber (1943), the variety was introduced by H. S. Sanford from Mediterranean Europe about 1875.  Although the seasons of maturity are similar, it is altogether different from the Garey's or California Mediterranean Sweet, which appears to be the distinctive old Maltaise Ovale variety of the Mediterranean basin.

Midknight (Midnight Valencia)
      Midknight is a virtually seedless, medium-large, somewhat oblong fruit of excellent quality and medium-late maturity.  Marloth and Basson (1955) regard this South African variety as an early Valencia selection and it is commonly called Midknight Valencia.  Since it ripens earlier than Valencia and does not fruit in clusters to the same degree, it is probably best considered a variety.  The tree is moderately vigorous and upright-growing, with large, broad leaves, but not as productive as standard Valencia.
      It originated on the place of A. P. Knight at Summerville, Addo, eastern Cape Province, as a selection from a rather variable lot of budded trees ordered from Westfalia Estates (northern Transvaal) in 1927.  Unfortunately, more than one clone seems to have been propagated under the same name, for two are now recognized—that characterized above and another of which the fruit is round and the tree less vigorous and more spreading.  Neither clone is currently of much importance.

Mohn
      See under Armstrong.

Moss
      This South African variety is a Cape Seedling selection made several decades ago by H. E. Moss of Grahamstown, eastern Cape Province.  The fruit somewhat resembles Valencia but is seedier and ripens earlier.  The parent tree is reported to have been about a century old at the time of its selection.  It has not been planted much and is no longer recommended.

Muden
      Muden produces a medium-small, comparatively few-seeded, round fruit of midseason maturity.  The tree comes into bearing very early and is regularly and heavily productive.  The fruit does not hold well on the tree, however, and fruit size diminishes appreciably as the tree ages.  This South African variety originated as a limb sport of Valencia in an orchard of the Golden Valley Citrus Estate at Muden, Natal Province.  Muden was found and first propagated in 1945.  It was rather extensively planted at Muden and in eastern Cape Province for a time but has been little propagated in recent years.

Oasis
      See under Casa Grande.

Olinda Valencia
      This California selection is a chance seedling, presumably of Valencia, found by H. J. Webber and L. D. Batchelor of the Citrus Research Center, Riverside, in the dooryard of O. Smith at Olinda in 1939 and released in 1957.  It is indistinguishable from Frost Valencia and hence is considered to be of nucellar origin.  Olinda is currently popular in California.

Omana Jaffa
      Omana Jaffa is a local selection of Jaffa that is currently popular in New Zealand as a late midseason variety.

Oom Louis
      This South African variety is a medium-sized, comparatively few-seeded, globose to oblong, very juicy fruit of midseason maturity.  The tree is vigorous, early bearing, and productive.  Fruit quality is excellent on Empress mandarin rootstock but poor on rough lemon.  Oom Louis originated as a chance seedling of Cape Seedling parentage on the property of the South African Railways near Hectorspruit station, eastern Transvaal, where it was selected by L. P. deVilliers of Nelspruit in 1944.  It has been planted commercially to some extent in eastern Transvaal.

Oranger des Baleares
      See under Fuya Menuda.

Oranger de Soller
      See under Fuya Menuda.

Ovaletto di Calatafimi
      This is a long-oval, late-maturing, usually seedless fruit of medium size and good quality.  The variety came to notice in the Calatafimi district near Tropani, Sicily, sometime between 1910 and 1920.  It is considered to be a derivative, probably a bud mutation, of the Calabrese Ovale variety (Fatta Del Bosco, 1963).

Pajarita (Pajarito)
      The Pajarita of Spain is a moderately seedy, medium-small, comparatively thick-rinded fruit of relatively low juice content, mediocre quality, and midseason maturity.  It is an old variety that has long been replaced with better varieties.

Paperrind (St. Michael, Paper Rind St. Michael, San Miquel)
      The fruit of this midseason California variety is small-sized, moderately seedy, juicy, and well-flavored.  The rind is very thin, leathery, and smooth.  The tree is vigorous, upright, and productive.
      Said to have originated on the Island of St. Michael, Azores Islands, presumably as a seedling, this variety was named and introduced about 1870 by T. A. Garey, pioneer citrus nurseryman of Los Angeles.  Along with Garey's Mediterranean Sweet, which ripens earlier, it soon attained importance as a midseason variety filling the gap between the early Washington navel and the late Valencia oranges.  As the California industry expanded with overlapping production of the latter two superior varieties, the popularity of Paperrind and Mediterranean Sweet declined and both have now virtually disappeared.  Although widely distributed to other countries, Paperrind seems to have achieved importance elsewhere only in Mexico, where it is known as San Miquel.

Partin Delicious
      See under Delicious.

Paterson (Paterson River)
      The Paterson is an Australian selection of Parramatta Seedling that originated on the Paterson River near Maitland, New South Wales.  Characterized by uniformity in shape and quality, this variety became popular following World War I, but has largely been replaced by the Washington navel.  Commercial plantings have not been made for several decades, although some old orchards still remain.

Peret (Berna Peret, Vernia Peret, Pereta)
      A comparatively new, late-maturing seedless variety, the fruit of Peret of Spain is indistinguishable from Berna, but according to Gonzalez-Sicilia (1963) colors earlier and more intensely and is juicier and sweeter.  These differences have not been confirmed in limited comparisons in Morocco.⁷  The tree is said to be more vigorous, larger, and more regularly productive than Berna but somewhat less cold-resistant.
      This variety is reported to have been found in an old seedling orchard in the Vergel district of Alicante province about 1911, but it was not propagated and promoted until much more recently.  It is currently planted to some extent in northern Alicante and southern Valencia provinces.

Perry
      The Perry of California is a limb sport of Valencia with fruit which is deeper in color (reddish-orange) and matures somewhat later.  It originated in the Perry orchard at Fillmore and was discovered by Howard Lorbeer of that community about 1956.  It appears to be promising and is currently under trial.

Plaquemines
      This Louisiana variety is a seedless budsport of Pineapple.  The two varieties are indistinguishable in appearance, but the fruit of Plaquemines averages slightly smaller, the rind is a little thicker, and maturity is somewhat later.
      The Plaquemines variety is one of twenty-three limb variations found in Pineapple trees at the Magnolia Orange Grove near Port Sulphur, Plaquemines Parish, and put under study in 1948.  Propagated soon thereafter and fruited for some years, it was released by the Louisiana Agricultural Experiment Station in 1960 (Hawthorne et al., 1960).

Prata (Branca)
      Prata produces a medium-large, spherical, highly seedy fruit of good flavor.  The distinctive feature of this variety and reason for its inclusion here lies in its pale yellow color.  It is an old variety of very limited importance in Spain and Portugal, found elsewhere only in collections.

Robinhood (Robin Hood)
      This South African variety produces a medium-sized, oblong to slightly oblique, virtually seedless, very juicy fruit of excellent quality and midseason maturity.  The tree is vigorous and productive.  Robinhood traces back to a budded parent parent tree of the Jaffa type on the farm of a Mr. Pursglove in the Karino area of eastern Transvaal, which he recognized as superior and decided to propagate several decades ago.  Because of budunion "crease," it should be grown on rootstocks other than rough lemon.  A few commercial plantings exist in the Lowveld portion of the region of its origin.

St. Michael
      See under Paperrind.

San Miquel
      See under Paperrind.

Seedless Valencia
      This Australian variety is a bud variation of Valencia that differs from it in that the fruit is more oblong or oval in form, less seedy (occasionally one or two seeds), and matures earlier (late midseason).  The tree is vigorous and upright with large leaves that tend to be bunched, giving it a distinctive appearance, and is strongly alternate-bearing.
      Seedless Valencia is said to have been discovered in the orchard of W. Eathers at North Richmond, New South Wales, between 1920 and 1925.  Limited commercial production occurs in Gosford and other districts near Sydney, but this variety is unlikely to increase much in importance because of its alternate crop habit.

Siletta
      See under Seleta.

Tenerife (Blanche de Teneriffe) (fig. 4-11).
      The Tenerife variety of Spain produces a medium-sized, moderately seedy, midseason fruit of good quality that is pale yellow in color rather than orange.  An old variety that appears to have originated in the Canary Islands, it early spread to other countries.  In several countries, Tenerife has received favorable reports, but nowhere has it become commercially important.  Currently, it is considered to have promise in Egypt.

Torregrosa
      A moderately seedy, midseason fruit that resembles Cadena Punchosa, the Spanish Torregrosa is inferior in that it is somewhat smaller, the rind is much thicker, the juice content is lower, and the flavor more acid.  It was long ago replaced with better varieties.

Trovita
      This California variety is believed to be a Washington navel orange seedling.  The fruit is early maturing, medium-small, few-seeded, juicy, and pleasantly flavored.  The tree is vigorous, upright-growing, and productive, but with a tendency to alternate bearing.
      Trovita originated as a seedling from a fallen fruit, presumably of Washington navel, at the Citrus Research Center, Riverside, California, in 1916 and was released in 1935.  It was selected in 1928 and described and named by H. B. Frost, the name being Esperanto for "found." In comparison with the parent variety, the fruit is smaller, juicier, and of milder flavor.  The tree is more productive under desert conditions.  Trovita has achieved little importance in California, but is said to be promising as an early juice variety in the Negev region of Israel and elsewhere.

Valencia Temprana
      This Spanish variety produces a virtually seedless, small-sized, juicy fruit of good flavor that is early midseason in maturity.  It was long ago replaced with better varieties and is included here because it is the only Spanish variety of that name and obviously altogether different from the California-named Valencia variety of worldwide importance.

Westin
      The fruit of this Brazilian midseason variety is medium-small, virtually seedless, especially well-colored (deep orange), juicy, and richly flavored (relatively high acidity).  The shipping quality is reported to be good.  The tree is vigorous, spreading, large, and very productive.
      Formerly known as Clementina, to avoid confusion with the well-known Clementine mandarin, it was recently renamed in honor of Professor Philippe Westin Cabral de Vasconcellos and is considered to be among the most promising midseason varieties for Brazil.

Yousef Solimon (Mazizi)
      This Egyptian variety produces fruit similar to the Egyptian baladi, but it is less seedy, the rind is thinner and of smoother surface texture, the flesh is juicier and richly sweet with less acid, and the fruit is earlier in maturity (early midseason).  The tree is moderately vigorous, medium-large, and upright-growing, with somewhat sparse foliage that consists of long, narrow leaves.  Yousef Solimon is an irregular and poor bearer.
      This variety was found in a baladi seedling orchard in Upper Egypt owned by Yousef Solimon and is popular in the local markets because of its rather distinctive flavor.

Zegzel
      This Moroccan variety is a midseason, seedling clone.  The fruit is medium-sized, subglobose to round, well-colored, and seedy, with roughly pebbled, easily peeled rind of medium thickness and juicy flesh of good flavor.  The fruit holds well on the tree, with little loss in quality though with some puffing of the rind.  The tree is vigorous, highly productive, upright-growing and large, with dense foliage consisting of large leaves.
      An old beledi selection that originated in the Zegzel Valley of eastern Morocco, Zegzel formerly was of considerable importance and exported to Europe.  The variety is now only of local popularity and no longer propagated.  It is of interest to note that Zegzel has been grown almost entirely as seedling trees.

Sugar or Acidless Oranges

      The sugar or acidless oranges are a small group of very low acid varieties that corresponds to the sweet lemons, limettas, and limes because of their lack of acidity, their insipidly sweet flavor, and the presence on the seeds of a cream-colored chalazal spot, which is darker on the more acid forms of citrus and chestnut-brown for the common sweet oranges (Chapot and Praloran, 1955).
      They are variously referred to as the douceâtre or douce (France), sucreña (Spain), Maltese or dolce (Italy), meski (North Africa and the Near East), moghrabi (Near East), lokkum or Tounsi (Turkey), succari (Egypt), and lima (Brazil) oranges.  With the exceptions given above, they are indistinguishable from the common sweet orange and several have marked resemblances to certain varieties of that group.⁸  There is at least one acidless navel orange variety, however—Bouroubaine Meski of Tunisia, and a pink-fleshed acidless variety, Vainiglia Sanguigno of Italy.  It has recently been shown, however, that this latter variety is not a true blood orange since the principal pigment involved is the carotenoid lycopene rather than an anthocyanin (Huet and Chapot, 1964).  The Mosambi variety of India has sometimes been regarded as a member of the sugar orange group, but the dark brown color of the chalazal spot indicates otherwise.
      Several independent origins are suggested for the sugar orange since at least three varieties so closely resemble varieties of the sweet orange as to strongly suggest a close relationship.  Thus, Shamouti Meski appears to be an acidless form of the famous Shamouti variety of the Near East, Maltaise Meski a non-acid form of the Maltaise Blonde of unknown origin, and there can scarcely be doubt that Bourouhaine Meski is a derivative from Bourouhaine of Tunisia.
      Because of the extremely low acidity of the flesh, sugar oranges attain edibility as soon as the juice content is moderately well developed and hence are the earliest to reach the local markets.  Moreover, their peculiar flavor is relished in most Arabic-speaking countries and to some extent in Spain and Portugal and their former colonies.  As a consequence, their culture has remained profitable, although they are obviously not suitable for export to major population centers of Europe or the United States.  In the Mediterranean area, Spain and Egypt are the countries where their culture is most important, and in the Western Hemisphere they are popular in Brazil and Mexico.  This type of orange may eventually prove to be valuable for breeding purposes (Soost and Cameron, 1961).

      Major Sugar Orange Varieties.—The varietal situation for both major and minor sugar orange varieties is most uncertain, yet it is clear there are a number of varieties, only a few of which are sufficiently distinctive to be identifiable with certainty.  To judge from the writer's personal knowledge and descriptions in the literature, the variety most widely grown and hence most important occurs under many local names which in reality are synonyms.  It is therefore his opinion that some of the characterizations given below almost certainly relate to the same horticultural variety.

Canamiel
      See under Sucreña.

Dolce
      See under Vainiglia.

Grano de Oro
      See under Sucreña.

Imperial
      See under Sucreña.

Lima
      Fruit medium-small, spherical to subglobose; seeds comparatively few.  Rind medium-thick; surface slightly rugose; color light orange.  Flesh color light yellow; tender and juicy; flavor insipid because of lack of acid.  Very early in maturity.
      Tree vigorous, large with dense foliage, and highly productive.
      Lima is said to be the most important of the three non-acid orange varieties grown in Brazil, where this fruit is so highly appreciated that it currently constitutes about 10 per cent of the plantings.  It is accorded particular dietary values for adults and is reported to be especially popular with children.

Maltese
      See under Vainiglia.

Mosambi
      See under Mosambi.

Real
      See under Sucreña.

Succari (Sukkari)
      Fruit small to medium-sized, somewhat oblate to globose; seedy.  Rind medium-thick and surface relatively smooth.  Good color at maturity.  Flesh color pale and juice abundant, but almost devoid of acid.  Sugar-acid ratio of 90-100:1 at maturity.  Matures early (October-December).
      Tree vigorous, upright, and productive.
      Of unknown origin, Succari has long been popular in Egypt and is of considerable commercial importance.

Sucreña (Imperial Grano de Oro, Real, Canamiel) (fig. 4-12)
      Fruit medium-small, variable in form, but prevailingly subglobose to spherical; moderately seedy, chalazal spot cream-colored.  Rind medium-thick and moderately pebbled.  Well-colored at full maturity.  Flesh color good at full maturity at which stage juice content is moderately high.  Flavor insipid owing to lack of acidity.  Of comparatively short season, it is commonly harvested prior to full maturity, at which stage color is pale and juice content and quality poor.  Earliest of all oranges.
      Tree vigorous, somewhat upright, medium-large, and productive.
      This variety is grown in Spain under a number of names, which reflects the fact that it has considerable local use though minor economic importance.  The fruit is said to be distasteful to most palates but much appreciated by those accustomed to it or intolerant of acid.  The vitamin C content is reported to be not appreciably lower than in other oranges.

Sukkari
      See under Succari.

Vainiglia (Vaniglia, Maltese, Dolce)
      Fruit medium-small to medium, subglobose to spherical; small apical depression; seedy.  Rind medium-thick and finely to moderately pebbled.  Well-colored at maturity.  Juicy and sweet flavored but lacking in acid and with slight bitterness, though eating quality generally improves with age.  Very early in maturity.
      Tree vigorous, medium-sized, and very productive.
      In Italy, this variety is very old and is thought to be of local origin.  Because of its insipidly sweet and faintly bitter taste, the demand for Vainiglia is said to be very limited and entirely local.
      Of special horticultural interest is the presumption that it gave rise to the unique, pink-fleshed, non-acid Vainiglia Sanguigno variety, which is not a true blood orange.
      The similarities reflected in the characterizations of the four varieties discussed in this subsection are such as to make it highly likely that they represent a single clone.

      Minor Sugar Orange Varieties.—The following seven sugar orange varieties appear to be the best known among those of local importance.

Bourouhaine Meski
      This is a Tunisian variety which Chapot and Huet (1964) state is an acidless form of the distinctive Bourouhaine navel orange variety, believed to be native to that country.

De Nice (Orange de Nice)
      This sugar orange, a variety of the French Riviera, is so similar to the Succari of Egypt and Meski of Tunisia as to be indistinguishable to the writer.

Iaffaoui Moghrabi
      See under Shamouti Meski.

Meski
      According to Chapot and Huet (1964), Meski is a Moroccan variety.  The writer found it indistinguishable from the De Nice of France, Succari of Egypt, Mogbrabi of Lebanon, and the common Meski of Tunisia.

Maltaise Meski
      This is a non-acid Tunisian variety that Chapot and Huet (1964) state is otherwise indistinguishable from the highly distinctive Maltaise Blonde (Petite Jaffa) variety.

Orange de Nice
      See under De Nice.

Piralima
      This Brazilian variety is much like the Lima but the fruit is reported to be somewhat flatter in form, the rind surface smoother and paler in color, the seed content a little lower, and the tree somewhat more productive.  Of considerable importance and second to the Lima in Brazil, Piralima is a selection of Lima made in the Piracicaba area by Professor P. Westin Cabral de Vasconcellos.

Serrana
      The Serrana of Brazil is a smaller, oval-shaped, and less juicy fruit than Piralima, with a thin, very smooth rind.
      It is reported to be an unstable clone, presumably chimeric in nature, that occasionally gives rise to limb sports which produce fruits of quite different characteristics.  Considered to be of local origin, the Serrana is of limited importance.

Shamouti Meski or Shamouti Moghrabi (Iaffaoui Moghrabi)
      Chapot (1954) reports that this Lebanese variety is indistinguishable from the famous Shamouti (Palestine Jaffa) except that it is seedier and almost tasteless.

Pigmented Oranges

      The pigmented oranges are the blood oranges of the Mediterranean basin (sanguina of Spain, sanguine of French-speaking countries, and sanguigna and sanguinella of Italy).  They differ in appearance from the common sweet oranges only because under certain conditions the fruit usually exhibits pink or red coloration in the flesh and juice and on the rind.  The blood oranges, in general, are characterized by a somewhat distinctive flavor that is much appreciated by connoisseurs and causes certain varieties to be regarded as among the most delicious of oranges.  The coloration of the blood oranges is associated with the development of anthocyanin pigments, whereas the pink and red coloration in the pigmented grapefruits is caused principally by the carotenoid pigment lycopene.  These pigments tend to deteriorate during processing and impart a muddy color to the juice.
      Most blood orange varieties appear to have originated in the Mediterranean basin, probably first in Sicily or Malta where they have been known for several centuries.  Although grown to some extent in many of the Mediterranean countries, their commercial culture is confined principally to Italy, Spain, Algeria, Morocco, and Tunisia.  They enjoy high favor in European markets in general and are especially popular in central and northern Europe.  The lack of dependability of blood coloration development in most varieties, however, is currently an important handicap and, together with technical difficulties in processing the juice, constitutes the principal deterrent to expansion of their culture.  Neither the producer nor the marketing agency can guarantee to provide the consumer with a uniform product with respect to either internal or external pigmentation, which is obviously requisite to standardization.
      The conditions responsible for the development of the blood coloration are not well understood and may differ somewhat for the flesh and rind.  It is clear that a certain amount of heat is a requisite, for intense coloration does not occur in the cool equable coastal region of southern California.  Color development is much less regular and intense in humid climates, such as Florida, than in arid climates such as the inland valleys of California where the diurnal fluctuations in temperature are much greater.  Cold storage materially intensifies flesh coloration.  Whereas moderate insolation seems to favor color development on the rind, intense sunlight appears to prevent or destroy it.  As a consequence, rind coloration is usually best on less exposed or partially shaded fruit.  In general, therefore, blood coloration in the flesh is most certain and intense in hot, dry, interior districts of the subtropics and rind coloration is best on non-exposed fruit.  That nutritional or other factors may be involved, however, is suggested by the observation that pigmentation is sometimes more intense on the fruit produced by trees on a particular rootstock and on trees of other kinds of citrus converted to blood oranges by topgrafting.
      Under comparable conditions, however, some varieties are more dependable in the development of the blood coloration than others and exhibit more intense pigmentation.  Those varieties in which blood coloration is most regularly and strongly expressed are commercially preferable and constitute the deep blood group (sanguine of French-speaking countries).  The conclusion that the deep blood varieties form a natural group has been materially strengthened recently by the studies of Chapot (1963e).  Chapot reports that the three varieties most certain of blood coloration under a wide variety of conditions and most intense in pigmentation under favorable conditions—Spanish Sanguinelli, Tarocco, and Moro—exhibit purplish-red coloration of the chalazal spot.  In contrast, the other blood varieties available for comparison showed chalazal spot coloration not significantly different from the normal chestnut-brown of non-blood oranges.  The less dependable and usually less intensely pigmented varieties comprise the light blood group (sanguinello of Italy, demi-sanguine in French) and are much more numerous and highly variable in behavior.
      Blood oranges have originated in three, widely separated areas of the Mediterranean basin, giving rise to three regional groups, in two of which parental relationship is either known or indicated.  As described and characterized by Chapot (1963e), these groups are as follows:
      The Ordinary Blood Oranges.—This is the oldest group, almost certainly of Sicilian origin, the fruits of which are similar to the common sweet orange with the exception of the blood pigmentation.  It includes the very old Sanguinello Comune and Maltaise Sanguine varieties, many other light blood oranges, and the much younger Moro and Tarocco deep blood varieties.
      2. The Doblefina Varieties.—Thisgroup originated in Spain with the Doblefina (Doble Fina) variety, the parentage of which is unknown, and all members are derivatives from it and exhibit many of its highly distinctive characteristics.  It consists of the relatively old parent variety Doblefina, Entrefina, the fairly new Doublefine Ameliorée (Washington Sanguine), and the very new deep blood Spanish Sanguinelli varieties.
      3. The Shamouti or Palestine Jaffa Blood Oranges.—This group, smallest of the three, originated in Lebanon or Syria.  Each member is identical with its parent variety with the exception of the degree of blood pigmentation.  It consists of Shamouti Maouardi, a light blood Shamouti, and Maouardi Beladi (Damawi), a light blood form of the beladi orange, which gave rise to Shamouti.
      Mention should perhaps be made also of two pink-fleshed orange varieties in which the coloration is caused by the carotenoid pigment lycopene instead of an anthocyanin.  Huet and Chapot (1964) have recently reported this to be the case in the old Vainiglia Sanguigno variety of Italy, and Monselise and Halevy (1961) have found a similar situation in the new Sarah variety of Israel, which originated as a budsport of Shamouti.
      While specific statistics are not available, Burke (1961) reported that blood oranges comprised 42 per cent of the Spanish orange production in 1961.  Competent observers have estimated that this percentage is higher in Italy.  Allowing for the production in Algeria, Morocco, and Tunisia, a conservative estimate of the 1965 commercial production of pigmented oranges appeared to be not less than 30 million boxes (70-lb equivalents), and probably more.  Moreover, from the trends of recent years, production may be expected to increase significantly in both Spain and Italy.  Because of the pigmentation of the juice, the blood oranges are not well adapted to processing and must therefore be marketed fresh.
      Some more or less general practices, unique to the production of blood oranges, may be noted.  In some districts in North Africa, differential harvesting reportedly is employed to separate the pigmented fruits from the non-pigmented.  The most practicable means of such harvesting is said to consist of picking the north and south sides of the trees separately.  A highly restricted practice which is said to be used beneficially by some growers in West Pakistan consists of shading the lower portion of the trees by means of a tall, rapid-growing covercrop such as sesbania (Sesbania exaltata).  This is reported to appreciably increase the percentage of pigmented fruits.

      Major Pigmented Orange Varieties.—The principal pigmented orange varieties of the world are presented below.

Belladonna Sanguigno
      See under Moro.

Blood Oval
      See under Doblefina.

Bloodred (Blood Red Malta)
      Bloodred is a seedy, light blood orange of very good flavor, but without distinctive characteristics, that is widely grown in the Punjab region of India and West Pakistan and is much prized there and in northern India.  The development of blood coloration is highly variable and uncertain and is best in the submontane districts, where the fruit attains good color and excellent flavor.
      The origin of this variety is unknown but almost certainly it came from the Mediterranean basin.

Calabrese Sanguigno
      See under Tarocco Liscio.

Doblefina (Oval Sangre, Sanguina Oval, Rojo Oval, Sanguine Ovale, Morlotte, Blood Oval) (fig. 4-13)
      Fruit medium-small to small, oval to oblong; virtually seedless.  Yellowish orange at maturity, more or less densely blushed with rose-colored flecks.  Rind medium-thick, firm and leathery; surface very smooth and fine-textured; tightly adherent (difficult to peel).  Flesh firm and moderately juicy, with pink flecks scattered more or less throughout; distinctive fragrance and mild, pleasant flavor.  Fruit hangs poorly on tree and drops badly, but ships and stores unusually well.  Late midseason in maturity.
      Tree small and somewhat lacking in vigor, spreading and open in growth habit; foliage sparser and lighter green than most.  An early and heavy bearer.
      Aside from its short season, lack of juiciness, and other faults, the Doblefina variety is highly variable and uncertain with respect to development and intensity of the blood coloration, which is often deficient or lacking.  When well developed, however, the fruit is attractive.
      Of unknown Spanish origin, Doblefina was for many decades the principal blood orange variety in Spain and was favorably known in European markets.  It has been losing ground for some years, however, to other varieties of better color and richer flavor, particularly its derivative, Spanish Sanguinelli.  It is of interest to note that three blood orange varieties—Entrefina, Doublefine Ameliorée, and Spanish Sanguinelli—have originated as budsports from Doblefina.

Doublefine Ameliorée (Grosse Sanguine, Washington Sanguine, Washington Sangre, Pedro Veyrat) (fig. 4-14)
      Fruit medium-large, oval to oblong, often asymmetric; commonly with persistent style or small shallow-embedded navel; seeds few and rudimentary or none.  Under favorable conditions external blood coloration good (better than Doblefina).  Rind medium-thick, moderately smooth, and not as tightly adherent as in Doblefina.  Flesh moderately juicy, but blood coloration commonly poor or lacking.  Flavor good.  Holds well on tree (very much better than Doblefina) and stores and ships as well or better.  Late midseason in maturity.
      Tree lacking in vigor, small, very precocious, and productive.
      This relatively new variety is said to have originated as a lima sport of Doblefina that was found by Balthazar Ferrer at Sagunto, Spain.  It has remained a minor variety in Spain, but is currently the leading blood orange variety in Algeria and Morocco.  The blood coloration is variable and uncertain and lacking in the Atlantic coastal districts of Morocco.

Entrefina (Inglesa)
      Fruit small, globose to very slightly oval; seeds very few.  Color similar to Doblefina, but even less certain in development of blood coloration.  Rind surface less smooth than Doblefina, but flesh somewhat juicier and fruit holds better on the tree.  Late midseason in maturity.
      Tree said to be more vigorous, larger, and more productive than Doblefina and less subject to dropping of the fruit.
      Entrefina is generally considered to be a subvariety or selection of Doblefina, with which it is often confused.  Because of its smaller size and less attractive appearance, this variety commands lower prices than Doblefina and has lost materially in importance.

Grosse Sanguine
      See under Doublefine Ameliorée.

Inglesa
      See under Entrefina.

Maltaise Sanguine (Portugaise)
      Fruit medium-sized, oblong to globose; seeds few to none.  External blood coloration well developed under favorable conditions.  Rind medium-thick, moderately pebbled, somewhat soft, and peels easily.  Flesh tender, melting, and very juicy, with good blood coloration under favorable conditions.  Flavor and aroma excellent.  Late midseason in maturity.  Holds on tree only moderately well and stores and ships poorly.
      Tree moderately vigorous, medium-large, and not very productive.  Some tendency to alternation.
      Portugaise is the name employed in Algeria where this variety is commercially most important, but in Tunisia it is the old and highly reputed Maltaise Sanguine variety.  Almost certainly a number of clones are involved which are indistinguishable in general, yet exhibit minor differences in growth habit and fruit form.  In Tunisian usage, Portugaise is considered to be somewhat more upright in growth habit and with fruit of a slightly more pronounced oval form.  There is a close resemblance between Maltaise Sanguine and the Sanguinella Moscata variety of Italy.
      There is general agreement as to the excellent eating quality and fragrance of this variety.  However, it is highly variable and uncertain with respect to blood coloration development.  Frequently external red pigmentation is not accompanied by internal coloration and in some growing areas both are lacking.
      The origin of this undoubtedly very old variety is unknown, but possibly it may have been the island of Malta.  The Maltese Blood variety introduced into Florida from the Mediterranean many years ago seems likely to be a clone of this variety as does the Bloodred Malta of West Pakistan and Punjab, India.  The Egyptian variety Baladi Blood, which is said to have been imported from Malta about 1830, almost certainly is Maltaise Sanguine.

Morlotte
      See under Doblefina.

Moro (Belladonna Sanguigno) (fig. 4-15)
      Fruit medium to medium-large, subglobose, round or obovoid; base somewhat furrowed; apex commonly flattened; areole faint or lacking; seeds few or none, but with chalazal spot purplish-red.  Rind medium-thick, moderately adherent, and somewhat pebbled.  Orange-colored at maturity with light pink blush or red streaks at advanced maturity.  Flesh deeply pigmented (almost violet-red); juicy; flavor pleasant.  Very early in maturity (earliest of the commercial blood oranges), but holds well on the tree and stores and ships well.  A distinctive aroma develops with advanced maturity, but flavor deteriorates if held too long in storage and becomes objectionable to some.
      Tree of medium vigor and size, spreading and round-topped; very productive fruit (generally in clusters of three or more).
      Moro is distinctive in that pigmentation develops early and strongly in the flesh, ranging from medium to intense, whereas rind pigmentation may be lacking or at best only moderately developed.  Thus, the Moro does not develop external pigmentation in the coastal area of southern California, where conditions are unfavorable to development of blood coloration, but almost always exhibits far more internal coloration than any other variety.  This variety undoubtedly belongs to the deep blood group.
      Of comparatively recent Sicilian origin and thought to have developed from the Sanguinello Moscato variety, Moro did not attain the popularity of Tarocco for several decades.  More recently, it has been planted to a considerable extent in Sicily, where it now enjoys equal favor.

Murtera
      Fruit medium-small, spherical to slightly oval; areolar ring in many cases; seeds few.  Color orange at maturity with light red blush.  Rind medium-thin with finely pebbled surface.  Flesh juicy but generally lacking in red coloration.  Flavor rich and sweet.  Hangs well on the tree, better than either Doblefina or Entrefina, and ships well.  Late midseason in maturity.
      Tree vigorous, medium-large, very productive, and hardy; foliage dense and dark-green in contrast with Doblefina.
      The principal fault of this Spanish variety is the poor blood coloration of both rind and flesh, particularly the latter.  As a consequence, Murtera's popularity has declined in favor of such better colored varieties as Spanish Sanguinelli.

Oval Sangre
      See under Doblefina.

Pedro Veyrat
      See under Doublefine Ameliorée.

Portugaise
      See under Maltaise Sanguine.

Ruby (Ruby Blood)
      Fruit medium-sized, globose to slightly oblong; faint areolar circular furrow or ridge; seeds relatively few.  Well-colored, withreddish flush under favorable conditions.  Rind medium-thick, finely pitted, and lightly pebbled.  Flesh tender and juicy; flavor rich.  Flesh color orange, streaked (rather than flecked) with red under favorable conditions.  Midseason in maturity.
      Tree moderately vigorous, compact, medium-large, and productive.
      The Ruby variety was introduced from the Mediterranean (country unknown) to Florida about 1880 and brought to California not long thereafter.  From its appearance and behavior, it may prove to be an old Italian variety.  In both Florida and California, Ruby is highly uncertain and variable with respect to development of blood coloration.  For this reason, it has not become popular and remains merely a novelty.  In California's coastal region, it never develops red pigmentation.  Ruby is at its best, with marked variability, however, in hot interior districts.  In such districts, the quality is excellent and part of the crop colors beautifully.
      Several unnamed clones or selections are known to exist which differ in blood coloration development and other minor respects.

Rojo Oval
      See under Doblefina.

Sanguigna Oval
      See under Doblefina.

Sanguigno Semplice
      Fruit medium-sized, globose; base slightly flattened; moderately seedy; yellowish-orange, and red-tinted at maturity (more so than Sanguinello Comune).  Rind medium-thick, moderately tough and adherent, and moderately to strongly pebbled.  Flesh juicy, pleasantly flavored, and streaked with red (much less intensely pigmented than the rind).  Midseason in maturity, but holds well on the tree.
      Tree similar to Sanguinello Comune in nearly all respects.
      Of unknown Sicilian origin and no longer planted, Sanguigno Semplice is believed to be the oldest blood orange variety in Italy.

Sanguinella Negra
      See under Spanish Sanguinelli.

Sanguinelli
      See under Spanish Sanguinelli.

Sanguinello Comune
      Fruit medium-sized, obovoid to oblong; base strongly furrowed and sometimes with small and very short neck; seeds few or none.  Orange-colored at maturity, washed with red.  Rind medium-thick, moderately tough and adherent, and moderately to strongly pebbled.  Flesh rather deeply red pigmented at maturity (more so and earlier than rind); juicy; pleasantly flavored.  Midseason in maturity.  Stores and ships moderately well.
      Tree of medium vigor and size; productive.
      An old Italian variety of unknown origin, Sanguinello Comune has long been one of the most important blood oranges of Sicily.
      From the literature it is not clear whether it is a true horticultural variety or a group of similar and presumably closely related clones.  It appears not to be a synonym of Sanguinello Moscato, however, though there are strong resemblances and they are doubtless closely related.

Sanguinello Moscato (fig. 4-16)
      Fruit medium-large, subglobose, round, or oblong; neck strongly furrowed (more pronounced than Sanguinello Comune); few or no seeds.  Orange-colored with the apical portion strongly red-blushed.  Rind medium-thick, somewhat pebbled, and moderately adherent.  Flesh very juicy; very well flavored; aromatic; usually well blood-colored.  Midseason in maturity and holds well on tree and ships well.
      Tree vigorous, large, symmetrical in form; very productive with most of the crop borne inside, where it is protected against climatic vicissitudes and uniformity in pigmentation is favored.
      According to Casella (1935a), this is a subvariety of Sanguinello Comune which is superior in certain respects that long ago caused it to become the principal variety in the Mount Etna region of Sicily.  Its superiority has given it a reputation in the export trade as the Paterno orange.
      The facts are not known concerning the origin of this old Sicilian variety but it is one or the most important and probably the most highly reputed blood orange.

Spanish Sanguinelli (Sanguinelli, Sanguinella Negra) (fig. 4-17)
      Fruit said to be similar to Doblefina, but larger, seedier, and often asymmetrical; persistent style; blood coloration of both rind and flesh much more intense and constant.  External red pigmentation rarely equalled by other blood oranges and excelled by none, making the fruit most attractive.  Reported to hold on tree longer than Doblefina and to store and ship fully as well or better.  Late midseason in maturity.  Intensity of external pigmentation and purplish-red color of the chalazal spot (Chapot, 1963e) place this variety in the deep blood group.
      Tree small to medium, spineless; foliage light green; productive.
      Spanish Sanguinelli is the preferred name to distinguish this new variety from the Italian light blood group (singular sanguinella, plural sanguinelli).
      The variety originated as a limb sport of Doblefina which came to light about 1950.  Its market reception has been excellent and it seems destined to replace the parent variety and most other Spanish blood oranges.

Tarocco (Tarocco dal Muso, Tarocco di Francofonte) (fig. 4-18)
      Fruit medium-large to large, variable in form from broadly obovate to globose; commonly with broad, pronounced, and furrowed basal collar; few or no seeds, the chalazal spots of which are purplish-red.  Yellowish-orange, blushed with red at full maturity.  Rind medium to medium-thick, moderately tightly adherent, and finely to moderately pebbled.  Flesh somewhat firm but juicy, usually well pigmented; flavor rich and sprightly.  Midseason in maturity (somewhat later than Moro and Ovaletto).  Loses quality if left on tree much past maturity and drops badly, but ships and stores well.
      Tree moderately vigorous, medium in size and irregular in form; foliage rather open, consisting of highly variable leaves, mainly oval-elliptical and sharp-pointed.  Sensitive to wind and neglect; only moderately productive.
      The name of this comparatively new Italian variety, the English equivalent of which is the peg-top toy, is said to have come from the pronounced basal collar that is characteristic of fruits of the original clone.  Scarcely three decades after its discovery, however, Casella (1935a) distinguished three types or clones, of which that known as Tarocchino is now considered to be the variety Ovaletto Sanguigno (Chapot, 1963e).

Tarocco Liscio (Calabrese Sanguigno, Tarocco Ovale)
      Fruit medium-large to large, variable in form from oval to obovate; commonly with broad neck in place of collar; sometimes with small navel; seeds few or none.  Rind medium-thick, somewhat more tightly adherent than Tarocco, and smooth to very finely pitted.  Internal characteristics and other features similar to Tarocco proper.
      Tree apparently somewhat less vigorous than Tarocco and more sensitive to wind and heat.
      That the two clones of Tarocco and Tarocco Liscio may exist as a chimeric mixture is suggested by Chapot (1963e), who reports that in Morocco fruits of both types often occur on the same tree.  The clone introduced into California several decades ago appears to be of the liscio type.
      Of unknown origin, but believed to have developed from Sanguinello Moscato, Tarocco was found by Dinaro Gesualdo in an orchard in the Carbone area of the Piedegaggi di Carlentini district of Siracusa Province, Sicily, shortly after the turn of the present century (Casella, 1935a).  Presumably because of its high quality, attractive appearance, and certainty of red pigmentation, it spread rapidly to other areas and is now widely planted in Sicily, generally distributed throughout Italy, and grown to some extent in Spain and Morocco.
      Tarocco is reported to have exhibited internal pigmentation wherever grown in the Mediterranean basin and usually some external coloration.  Its behavior in California corresponds with these reports, since some degree of internal coloration usually develops even in the relatively cool southern coastal region.  This behavior, coupled with the purplish-red coloration of the chalazal spot, indicates that Tarocco belongs to the deep blood orange group (Chapot, 1963e).

Tomango
      Fruit medium-small to medium, oblong to oval; occasionally with small navel; seeds few or none.  Rind medium-thin, comparatively smooth; color yellowish-orange at maturity.  Flesh tender and melting, very juicy; flavor excellent.  Midseason in maturity.
      Tree slow-growing, medium-small, and straggly upright in habit; leaves large, broadly lanceolate, and suggestive of the Jaffa variety.  Somewhat slow to come into bearing but productive.
      In South Africa, where the Tomango variety received its name and has considerable and increasing importance, it is not grown as a blood orange, since external pigmentation rarely if ever develops and internal coloration occurs only in seasons of unusually cold winters, when it is confined to small red flecks in the flesh.  Tomango is obviously a light blood variety that is grown under conditions unfavorable for the development of the blood pigmentation.
      The origin of this variety is unknown but it has been traced back to the Watkinson Nurseries of Nelspruit, eastern Transvaal, from whom a tree was obtained by H. L. Hall of Mataffin (same state) in 1906.  It seems likely that it is one of the Mediterranean light blood varieties.
      Tomango is one of the four midseason varieties recommended for commercial planting in South Africa (Marloth and Basson, 1955).

Washington Sangre
      See under Doublefine Ameliorée.

Washington Sanguine
      See under Doublefine Ameliorée.

      Minor Pigmented Orange Varieties.—Pigmented orange varieties of regional significance or minor commercial value are presented below.

Chemi
      The Chemi is an old Tunisian variety of local importance only.  The fruit is oblong and almost pyriform, because of a prominent, broad, elevated collar.  Both fruit and collar are sometimes slightly ridged.  External pigmentation is light or lacking, but internal blood coloration is commonly deep and approaches that of Moro but is less constant.  Chapot (1963e) remarks that although the name of Chemi translates as "Syrian" this variety is not now known in the Near East.

Damawi
      See under Maourdi.

Demmi
      Demmi (meaning blood) is currently the Libyan variety most popular for export.  The fruit is medium to medium small, slightly oblong-oval, and has a low seed content.  The rind is thin and tough and the flesh is firm but juicy and richly flavored.  Demmi is early midseason in maturity at which stage both flesh and rind are deep pink.  The fruit holds well on the tree, retains its quality, and stores and ships well.
      The tree is moderately vigorous and productive and more resistant to such unfavorable conditions as desert winds than other varieties.  Of unknown but apparently local origin, several clones of Demmi are recognized of which the one described here is preferred.  One clone, which should be avoided, apparently contains an infection that causes marked dwarfing associated with woody knots on the trunk and larger branches.

Doppio Sanguigno Signorelli
      This Italian variety produces an early midseason-ripening and coloring fruit that is almost seedless and of high quality.  The principal fault of Doppio Sanguigno Signorelli is low productivity.
      The writer has not been able to ascertain the current status of this and minor Italian vanities in this subsection which were described by Casella (1935a).  The fruit of Doppio Sanguigno Signorelli is similar in appearance to Sanguigno Doppio.  It is larger, however, and commonly has a small navel.  The rind is thicker, somewhat more roughly pebbled with some bloom, and more intensely red-colored at full maturity.  The flesh is also well-colored, juicy, and the flavor sweet and aromatic.
      The tree is somewhat lacking in vigor, with numerous pendulous branchlets, and of low productivity.
      Chapot (1963e) believes that this variety probably originated as a bud variation of Sanguigno Doppio.

Iaffaoui Maourdi or Mawardi (Shamouti Maouardi)
      This Lebanese variety is a light blood clone of the well-known Shamouti or Palestine Jaffa and indistinguishable from it except that under favorable conditions the rind is attractively rose-tinted and the flesh moderately blood-colored.  Chapot (1954) considers the variety to be of local origin.

Maltaise Boukhobsa
      This variety is a Tunisian selection of Maltaise Sanguine which is indistinguishable except that the fruit is much earlier in maturity and keeps better, and the leaves are narrower.  Chapot (1954) reports that this very new variety is the earliest to mature of all blood oranges.

Maouardi or Mawardi Beladi (Damawi)
      This light blood Lebanese variety of the beladi type is also of local importance in Egypt under the name Khalili Ahmer or Red (Egyptian Blood).  Chapot (1954) considers Maouardi to be of local Lebanese origin.

Ovaletto Sanguigno
      Ovaletto Sanguigno produces a very early ripening, lightly pigmented, nearly seedless, pleasantly flavored fruit.  It is a highly productive variety and the principal fault is poor and uncertain fruit pigmentation.
      The fruit is quite variable but usually medium to medium-large and oval to oblong with slightly flattened ends.  The rind is medium fine-grained, moderately thick, and slightly red-tinged at maturity.  The red-streaked flesh is of a pleasant flavor.  The fruit, which stores and ships well, matures shortly after Moro (the earliest blood orange) and drops badly if held long on the tree.
      The tree is vigorous, large, and regularly productive, more so than most other varieties.
      According to Casella (1935a), this variety came to light about the same time as Tarocco and in the same area.  Chapot (1963e) believes that Tarocchino, described by Casella as a derivative of Tarocco, is identical with Ovaletto Sanguigno.

Saasli
      Saasli is a virtually seedless, light blood Lebanese variety of unknown origin.  The fruit is oval in form, with a smooth, thin rind.  The flesh is melting, juicy, and of good flavor.  Under favorable conditions, the rind is highly pigmented but the flesh poorly colored.  The tree is vigorous but not very productive.  Saasli is of minor and local importance only in Lebanon, and Chapot (1954) considers it of local origin.

Sanguigno Doppio (Doppio Sanguigno)
      Sanguigno Doppio, an Italian variety, produces a midseason, seedy fruit of rough external texture and mediocre quality.  The variety has not been planted for decades, but still has importance in some of the older orchards and districts.
      The fruit is medium-small to medium in size, subglobose to spherical, flattened at both ends, and with a pronounced and furrowed basal cavity.  The rind is medium-thick, very roughly pebbled, red-splashed and striped at maturity, and puffs badly when overripe.  The flesh is poorly pigmented but pleasantly flavored.  The fruit loses quality rapidly if stored on the tree and does not store or ship well.
      This variety is considered to be one of the oldest blood oranges, but has never spread much beyond the area where it is presumed to have originated.

Sanguigno Zuccherino
      This Italian variety produces an early, midseason, few-seeded fruit that is of low quality and keeps and ships poorly.  Sanguigno Zuccherino has not been planted for decades, but still retains local importance in a few of the older districts of Italy.
      The fruit is medium-small, subglobose to round, deeply grooved at the base and has a small apical basin.  The rind is medium in thickness, soft and not strongly adherent, moderately pebbled, and pink-blushed at maturity.  The flesh is moderately pigmented, very juicy and sweet, and low in acidity.  The fruit is too flat in taste for most palates.

Shamouti Maourdi
      See under Iaffaoui Maourdi.

Vaccaro
      The Italian Vaccaro variety produces an attractive, midseason, few-seeded fruit of good quality.  This variety, which has distinctive tree characteristics, is of limited importance in the Paterno area.
      The fruit is of medium size, subglobose to spherical, shallow-furrowed at the base, and slightly flattened at the apex with a faint areolar ring.  The rind is medium-thin, leathery, and tightly adherent.  It has a smooth, glossy surface and is moderately splashed with pink.  The flesh is red-streaked, moderately juicy, and of agreeable flavor.  Seeds are few and small.  The fruit holds well on the tree.
      The tree is somewhat lacking in vigor and has a distinctive growth habit in that the main branches are horizontal rather than upright and the branchlets are slender, weak, and pendulous.

Navel Oranges

      The most distinctive feature of the navel oranges, in which they differ from all others, is anatomical in nature and consists of the presence of the navel—a small and rudimentary secondary fruit embedded in the apex of the primary fruit.  While the tendency to produce fruits with small navels is exhibited by a number of the mandarins and some other orange varieties, it is highly variable from season to season.  Only in the navel oranges does this phenomenon occur regularly.  Seedlessness also is characteristic of navel oranges, resulting from the fact that functional pollen is lacking and viable ovules are rare.
      Closely related to the navels is the seedy double orange (see Tunisian Bourouhaine), in which the secondary fruit is much larger, more deeply embedded, and usually devoid of rind.
      Other distinctive characteristics of most navel oranges include a crispness of flesh texture, ease of peeling and separation of the segments, and richness of flavor, which under favorable climatic conditions combine to make navel oranges among the finest of dessert fruits.  These characteristics, added to the deep orange color navels usually develop, cause them to command a premium in most markets.
      With minor exceptions only, navel orange trees are less vigorous and more sensitive to unfavorable conditions of environment or neglect than most other oranges.  This is reflected in greater dwarfing on certain rootstocks, lower average production in many areas, and a much narrower range of climatic adaptation.  Navel oranges are poorly adapted to the humid tropics, semitropics, or intense desert heat.
      The navel orange was known in the Mediterranean basin several centuries ago, where it was described and figured by Ferrari (fig. 4-19), whose famous monograph on the citrus fruits was published in the seventeenth century in Rome (Ferrari, 1646).  Risso and Poiteau (1818-22) described a Portuguese navel orange variety.  Gonzalez-Sicilia (1963) states that local varieties of this fruit have long been known in Spain and refers to the preñado (pregnant) variety described by Giner Alino in 1893.  More recently, a conspectus of citrus varieties in Portugal (Bobone, 1938) lists and describes two navel oranges—Baia (Bahia of Brazil) and Comprida.  It seems clear, therefore, that navel orange varieties have long existed in Spain and Portugal and the likelihood seems good that the Portuguese introduced this fruit into Brazil where almost certainly the Bahia variety, which has come to be known as Washington, originated (Dorsett, Shamel, and Popenoe, 1917).
      Although importations of navel orange clones from Brazil were made to Australia as early as 1824 (Bowman, 1955) and to Florida in 1835 (Webber, 1943, p. 531), that which became known as Washington was received by the U.S. Department of Agriculture in 1870, propagated in Washington, D.C. under glass, and sent to California and Florida three years later.  The remarkable success of the introduction made in Riverside, California, led to its rapid commercialization and spread to other countries.
      Navel orange clones in general, and notably the Washington variety, appear to be unstable and especially prone to give rise to somatic mutations.  Indeed, with the possible exception of the so-called Australian variety and its derivatives, all the navel varieties treated in this subsection are known or believed to have originated from Washington, nearly all as bud or limb sports.  Moreover, this variety has given rise to several non-navel clones, among which are the Croc, Marrs, and Trovita varieties.
      Primarily because of the Washington and Bahianinha varieties, the navel oranges are of great commercial importance, ranking second only to the common sweet oranges.  Conservatively estimated, their annual production in 1965 was in the range of 45 to 50 million 70-pound box equivalents.  The principal navel orange producing countries are the United States (California), Brazil, Spain, South Africa, Australia, Morocco, and Algeria.
      The navel oranges are utilized primarily in the fresh form for eating out-of-hand, in fruit salads, as a dessert fruit, or as fresh juice.  Bitterness often develops when the juice is stored and is poorly adapted to processing.

      Major Navel Orange Varieties.—Theten navel orange varieties of greatest commercial significance are described below.

Atwood (Atwood Early)
      The fruit and tree of the Atwood navel orange variety are virtually indistinguishable from the parent variety, Washington.  The fruit colors slightly earlier and the rind surface appears to be somewhat smoother, however.  While earlier maturity is suggested by its coloring behavior, the fruit stores on the tree especially well without appreciable loss of quality.  During the early part of the season, however, its quality is not quite as good as that of the parent variety.
      According to Opitz (1962), Atwood originated as a limb sport in the orchard of Frank Atwood near Lemon Cove, California, and was first noticed about 1935.  It is considered to be promising in central California and has been planted to some extent there in recent years.

Australian
      Strictly speaking, this is a group of somewhat similar but inferior navel orange clones at least one of which was introduced from Australia into California prior to the successful establishment there of the Washington navel variety; such an introduction seems also to have occurred in South Africa.  Australian is therefore to be regarded as the name of a group or type rather than a variety.
      In general, the fruits are smaller than Washington, flatter in form, and sometimes broadly pointed at the apex.  The navel is smaller and more deeply embedded, and the rind is thicker and rougher.  The flesh is softer in texture and commonly juicier than the Washington, and the season of maturity is considerably later, the flavor remaining tart until late in the season.
      The trees are more vigorous, hardy, larger, and upright-spreading, rather than drooping as with the Washington.  Some clones are productive but with an alternate-bearing tendency; most, however, are erratic and unsatisfactory in production and commercially worthless.
      The origin of this type of navel orange is obscure, but it is known to have gone from Brazil to Australia, from whence it was probably taken to California and South Africa.  It may have originated in Brazil, as did the Washington variety, but it seems more likely to have been taken to Brazil from Portugal where a navel orange variety has long existed (Risso and Poiteau, 1818-22).  Although perhaps remote, the possibility clearly exists that this old Portuguese variety may have given rise to Washington.
      Because of its earlier introduction into California and South Africa and its propagation for some years thereafter, both countries experienced the problem of eliminating Australian-type clones from use in their orchards.  In California this was long ago accomplished through care in budwood selection and topgrafting orchard trees.  While no longer propagated in South Africa, there still remain old orchards of selected Australian-type clones, the principal two of which are reported to be Company and Pretoria (Marloth and Basson, 1959).

Bahia
      See under Washington.

Baiana
      See under Washington.

Baianinha Piracicaba (Bahianinha) (fig. 4-20)
      The two-word name Baianinha Piracicaba is preferable to distinguish this important variety from two smaller-fruited Brazilian selections, Ivers and Thomazzelli.
      The fruit is reported to differ from Washington navel principally as follows: (1) it averages considerably smaller in size; (2) the shape is slightly more oval; (3) it has a smaller and closed navel; and (4) the rind is thinner.  The tree is said to be productive but smaller and less vigorous than the Washington variety.
      In California, where this variety has been under observation for only a few years, the differences between this variety and Washington appear to be somewhat less than those reported in Brazil.
      The presumption is that thisvariety originated as a bud mutation from the Washington or Bahia navel orange.  Webber (1943) has presented evidence, however, that it may not have originated in Brazil, as commonly supposed, since it appeared in a planting of navel orange trees made at Piracicaba, São Paulo State, about 1907-08 with budded trees imported from the United States, presumably Florida.  That this variety is somewhat unstable and has subsequently given rise to other clones is clear from the literature and the existence of the two smaller-fruited selections mentioned above.
      Primarily because of its desirable size for export markets, Bahianinha Piracicaba soon became popular in Brazil and within a few years attained the status of the major early export variety.  It is said to constitute about a third of the commercial orange acreage of Brazil and is grown principally in São Paulo State.

Cram
      See under Washington.

Dalmau
      See under Navelina.

Eddy
      See under Washington.

Fisher
      See under Washington.

Frost Washington
      Frost Washington is the first, and currently much the most important, nucellar budline of the Washington navel.  It was originated by H. B. Frost, the geneticist and breeder, at the University of California Citrus Research Center, Riverside, from a controlled cross made in 1916.  It was not released until 1952, however.  Since that time its popularity has increased until it is now more widely planted in California, Arizona, and Morocco than any other clonal selection of Washington.
      In this connection, mention should be made of the now well-established fact that Frost already has given rise through bud variation to a new and much less desirable clone, characterized by a more acid fruit of later maturity.  In comparison to the Frost Washington, the fruit size and navel opening average smaller, the rind texture is coarser, and the flesh is more tender (Soost et al., 1961).

Gillette
      Fruit large, spherical; navel well developed but not prominent; seedless.  Well-colored.  Rind thick and moderately pebbled.  Flesh color, texture, and flavor similar to Washington.  Very early in maturity (about ten days earlier than Washington) and holds well on the tree.
      Tree vigorous and distinctive in appearance; leaves large, thick, cupped, and somewhat grapefruit-like, clustered toward the tips of erect branchlets.  Fruit said to be less subject to sunburn and splitting than Washington.  Moderately productive.
      In comparison with the Washington variety, the fruit of the Gillette is slightly larger and more spherical.  The rind is also somewhat thicker.  The tree is distinctively different in appearance.
      The origin of Gillette is unknown, but it is presumed to be a limb sport that was accidentally propagated about 1935 by the Gregg Nursery of Anaheim, California.  It came to light in 1945 when four scattered trees were found in an orchard owned by the Gillette Brothers at Hemet, California, which had been planted in 1936 by the Gregg Nursery.  Although not promoted by any nursery company, plantings of this variety now occur in all the more interior navel orange sections of California.

Leng (fig. 4-21)
      Fruit medium-small to medium in size, globose; navel uniformly small though well developed; seedless.  Color bright orange.  Rind medium-thin to medium and finely pebbled.  Flesh well-colored; texture medium; juicy; flavor only fair.  Very early in maturity (a week or ten days earlier than Washington), but fruit holds well on tree without loss of quality.
      Tree indistinguishable from Washington but fruit more susceptible to splitting and sometimes undesirably small.  A regular but moderate bearer.
      In comparison with Washington, fruit of the Leng variety reaches maturity slightly earlier, has a smoother, thinner rind, and is smaller, juicier, and poorer in flavor.
      This Australian variety originated as a limb sport of Washington in the orchard of A. D. Leng at Irymple, near Mildura, New South Wales, and first came to notice in 1935.  It is currently popular in the Murray River districts of New South Wales and Victoria and in South Australia.

Navelina (Dalmau)
      Fruit medium to medium-large, spherical to obovoid; basal end commonly strongly furrowed; navel small and not prominent, but opening not closed; seedless.  Color reddish-orange at maturity.  Rind medium-thin and smooth (approaching Thomson).  Flesh color deep; texture medium; rather juicy; flavor sweet (less sprightly than Washington).  Very early in maturity (fully as early as Thomson and perhaps a little earlier).
      Tree lacking in vigor, semi-dwarfed, and small (like Robertson); characteristic small dark green leaves give a distinctive appearance.  Productive.
      In comparison with Washington, the fruit of the Navelina variety averages a little smaller and has a much less prominent navel, the rind is smoother and deeper colored, and maturity is much earlier.  The flavor is not as rich and sprightly.  The tree is notably less vigorous and smaller.
      Gonzalez-Sicilia (1963) reports that this variety was received about 1933 from the Citrus Research Center, Riverside, California, under the name Early Navel (R5, T8, CES 574).⁹  The records at the Citrus Research Center show that the variety was accessioned about 1910 under the name Smith's Early Navel and was thought to be a budsport of local origin.  Under the Spanish name Navelina, presumably referring to the small tree, this variety is now available from several nurseries in Spain.  It is grown in Portugal under the name of Dalmau and is under trial in a number of other Mediterranean countries.  Currently, the principal center of commercial production is reported to be the Sagunto-Castellón district, north of Valencia, Spain.
      Chapot reports that two clones are recognized in Morocco.  That described above is called Dalmau (name of a Spanish nurseryman).  Another, similar in all respects except that the color of both fruit and leaves is less intense, goes by the name Navelina.¹⁰

Oberholzer (Oberholzer Palmer)
      Fruit similar to Washington, but smaller and with less conspicuous navel.  Early in maturity and holds well on tree.
      Tree more vigorous than Washington; upright-spreading; outstandingly productive.
      This new South African variety should not be confused with the Palmer Washington, a clonal selection that has been propagated to a small extent, or with the Ryan, sometimes incorrectly called the Palmer Nucellar.  The variety is recorded as Accession No. 503 of the Citrus and Subtropical Fruit Research Institute of Nelspruit, eastern Transvaal, South Africa.
      The possibility would seem to exist that this variety may have originated as a variation in a nucellar budline, for it came to light about 1950 as one of four trees sent to Nelspruit by P. C. J. Oberholzer of the University of Pretoria, who had propagated them with budwood taken from a group of ten trees whose bud parent was reported to be a Washington navel seedling of unknown origin.
      Oberholzer appears to be promising and has already been planted to a considerable extent in South Africa, where it is said to be the navel variety currently most in demand.

Original
      See under Washington.

Parent
      See under Washington.

Riverside
      See under Washington.

Robertson
      Fruit virtually indistinguishable from Washington except for medium-large size, slightly lower quality, and earlier maturity, which is usually ten days to two weeks.  While maturing about the same time as Thomson, quality is better and fruit is retained much longer on tree.  Because fruit is often borne in tight clusters, its shape is sometimes slightly distorted and exhibits flat contact surfaces.
      Tree lacking in vigor (more so than Thomson), small (markedly dwarfed on sour orange rootstock), heat-resistant, precocious, and very prolific.
      The heat resistance and associated high-yielding behavior of the Robertson navel orange appear to relate to the fact that, although it blossoms at about the same time as other varieties the young fruits develop more rapidly and pass through the fruit-setting phase earlier.  The fruits thus escape the severe dropping associated with the heat and dryness normally characteristic of the later fruit-setting period of other varieties (Coit and Hodgson, 1919).
      Robertson originated as a limb sport in an old Washington navel tree in an orchard near Redlands, California, where it was found by Roy Robertson in 1925.  It was patented (U.S. Plant Patent No. 126) by Armstrong Nurseries of Ontario, California, and introducer to the trade in 1936.  Although planted and topworked to some extent, it has not become commercially important in California or Arizona, nor apparently elsewhere.  However, because of its small tree size and early and high productivity, it is popular as a dooryard or container-grown patio tree.

Tibbets
      See under Washington.

Thomson (Thomson Improved) (fig. 4-22)
      Fruit medium-large, globose to slightly obovate or ellipsoid; occasionally with collar and commonly with two or three relatively deep and long radial basal furrows; apex usually protruded or broadly nippled or with large open navel; seedless.  Less well-colored than Washington.  Rind medium-thin and surface smooth and glossy though finely pitted.  Flesh well-colored with firmtexture; medium juice content; flavor good.  Holds on the tree poorly with rapid loss in quality.  Very early in maturity (10 days or more in advance of Washington).
      Tree less vigorous and more compact than Washington and commonly semi-dwarfed; also less cold- and heat-resistant.  Clone unstable, very likely chimeric in constitution, and exhibits tendency toward reversion.
      The Thomson variety originated as a limb sport of Washington in Duarte, California, and was named and introduced by the owner, A. C. Thomson, about 1891.  Because of the earliness and attractive appearance of the fruit, it was extensively planted for some years and introduced to other navel orange-producing countries such as Algeria, Morocco, Chile, and Australia.  Within a few years, however, its faults became so evident that planting was discontinued and most of the California acreage was converted or removed.  So far as can be determined, this has been its history elsewhere, with the possible exception of Chile.  Except for earliness of maturity, it is inferior to the parent variety in all respects.
      Dungan Thomson is the only selection of Thomson currently propagated in California.  The tree or trees employed are in an old and outstanding orchard of this variety at Exeter, the present owner of which is Jack Dungan of that locality.  Dungan Thomson has come into prominence recently because of renewed interest in the planting of very early maturing varieties in the San Joaquin Valley.

Warren
      See under Washington below.

Washington (Bahia, Riverside, Baia, Baiana) (fig. 4-23)
      Fruit large, spherical to obovoid or ellipsoid; base sometimes slightly collared; apex often slightly protruded or broadly nippled; navel medium to large and sometimes protruding navel; seedless.  Especially well-colored (deep orange).  Rind medium-thick, somewhat tender; surface coarsely pitted and moderately pebbled.  Flesh color deep; texture firm; moderately juicy; flavor rich.  Fruit holds on tree and stores and ships relatively well, but processes poorly.  Early in maturity.
      Tree round-topped, somewhat drooping, and medium in size and vigor.  Sensitive to heat and aridity during bloom and fruit-setting, and hence restricted in range of climatic adaptation.  Anthers cream-colored, for they are devoid of pollen.
      The origin of the Washington or Bahia variety is not known but, after a study at first hand, Dorsett, Shamel, and Popenoe (1917) of the U.S. Department of Agriculture concluded that it was probably a limb sport that was found in a tree of the Selecta variety near Bahia, Brazil, and first propagated some time between 1810 and 1820.  In the opinion of the writer, it is more likely that the parent variety was the Portuguese navel (Umbigo) orange described by Risso and Poiteau (1818-22) and that it originated somewhat earlier.
      The marked superiority of the new variety was noted by travelers and visitors and led to its introduction into Australia in 1824 and Florida in 1835.  It is known that trees were sent from Australia to California as early as 1870 (Coit, 1915, p. 16).  The introduction that led to adoption of the name Washington and to its commercialization in California and most other countries where it is now grown, however, occurred in 1870 when twelve budded trees were received from Bahia by William 0. Saunders, superintendent of gardens and grounds for the U.S. Department of Agriculture in Washington.  These were planted in a greenhouse and immediately propagated for distribution.  Several years later trees were sent to a number of persons in California and Florida.  Among those who received trees were L. C. Tibbets of Riverside, Alexander Craw of San Diego, and Edwin Kimball of Hayward (Butterfield, 1963, p. 34).
      It was the Tibbets planting, however, that resulted in the name Washington being attached to this variety and brought it into prominence.  It is believed that Tibbets received and planted three trees in his dooryard, located near the present junction of Central and Palm Avenues, two of which survived and became sources of budwood a few years later.  In 1903, one of these was transplanted to a location in front of the Glenwood Hotel (now the Mission Inn) where it survived only a few years.  At about the same time, the other tree became the property of the City of Riverside and was removed to its present location at the head of Magnolia Avenue, where it still exists, although in a condition of decline from which it seems unlikely to recover.
      Planted in March, 1874 (Mills, 1943), the Tibbets trees came into bearing early and the fruit soon attracted local attention.  Exhibited at a citrus fair in Riverside on January 22, 1879, by the Southern California Horticultural Society, it was awarded first prize over other navel oranges, all of which were from stock previously imported from Australia.  The Washington was so superior that enterprising nurserymen and growers propagated it extensively and within a decade or two it became the leading variety, a position it held for many years.  Thomas W. Cover, a local nurseryman and grower, who also exhibited it at the above-mentioned fair, is credited with having first propagated the Washington variety.  From California it early spread to other parts of the citricultural world and soon became a major variety, now second only to Valencia.
      As to whom credit is due for calling the Bahia navel orange to Mr. Saunder's attention and providing the budded trees received by him in 1870, the facts are somewhat uncertain.  Coit (1915, p. 17) states that a woman missionary stationed at Bahia was responsible, but Webber (1943, p. 531) credits F. I. C. Schneider, whom be states was the first Presbyterian missionary sent to Bahia.  It seems likely that both statements are correct and that the transaction involved both Mrs. Schneider and her husband, for in later correspondence Mr. Saunders stated that his correspondent was a woman.
      Although early introduced and planted extensively in Florida, this variety has proven to have only limited commercial value there.  It tends to produce poorly and the fruit is generally large, coarse-textured, and of poor quality.  It is clearly not well adapted to hot, semitropical climates.  There are several other navel varieties or local origin, however, that do much better in Florida and have been planted commercially in recent years, among which are Summerfield, Glen, and Dream.  So far as can be ascertained these are all seedling or mutant clones of obscure.
      Presumably having originated as a limb sport, Washington has exhibited a remarkable degree of somatic instability, giving rise by bud mutation to numerous clonal varieties and many chimeras.  That earliest recognized in California is Australian, which may have originated in Australia but more likely in Brazil.  It is more vigorous but commercially nearly worthless.  Some of the earlier introductions into Florida seem likely to have been mutant clones.  The principal varieties known to have originated in California as limb sports include Thomson, Carter, Robertson, Atwood and Gillette.  Of little or no importance are Navelencia, Nugget, Buckeye, Riverside Early, Surprise, Yellow, and Summernavel.  Several have been reported from South Africa and Australia.
      There are also a number of named clonal selections and at least one nucellar clonal budline currently under propagation.
      Although a number of outstanding trees have been selected and registered for use in propagation, three have been of principal interest in recent years, namely Eddy, Parent (Original, Tibbets), and Warren.  Eddy was named for the owner of a superior orchard in Arlington, California, the clone of which traces back to an outstanding tree at East Highlands.  Warren goes back to an outstanding tree near Glendora, California, that was selected by C. M. Warren, long-time prominent citrus nurseryman.  Parent, as the name and synonyms indicate, is the last remaining tree of the Tibbets introduction from Washington, D.C., and hence the original clone to which this variety traces in California.  Unfortunately, for some years past it has been declining in vigor and in 1967 seemed unlikely to survive much longer.  Other selections that have been used somewhat include Cram and Fisher.

      Minor Navel Orange Varieties.—Navel orange varieties of limited commercial importance or declining popularity are presented below.

Baddaford
      See under Flannagan.

Bellamy
      Fruit large, shape varying from oblate to obovate; navel small or lacking, rind of medium thickness and texture.  Well-colored, juicy, and of good flavor.
      Tree vigorous, upright, moderately thorny, and productive.
      The Bellamy variety of Australia originated as a chance seedling, presumably of the Washington navel, at Ourimbah, New South Wales, and was first planted commercially by a Mr. Bellamy of that community in about 1930.  It is recommended only for conditions not sufficiently favorable for Washington and seems not likely to achieve much importance.

Bourouhaine (Orange Double, Orange du Bey)
      Fruit medium-sized, oblate to subglobose; apex flattened or slight depressed and large; externally inconspicuous and deeply embedded navel which usually is completely without vestiges of peel and hence in cross-section gives the appearance of a double fruit.  Seedy when cross-pollination available, but seedless when not as viable pollen is not produced.  Juicy and flavor good.  Early in maturity but does not hold well on the tree.
      This is an old and highly distinctive variety in Tunisia that is considered to be of local origin.  It is believed to have given rise to the similar but acidless Bourouhaine Meski variety.

Buckeye (Golden Buckeye)
      Fruit oblong to ellipsoid; apex nipple-like, containing a closed navel; rind very smooth, thin, and leathery.  Yellowish-orange colored, with occasional narrow orange streaks or ribs.  Matures considerably earlier than Washington.
      Tree slow-growing, small, and weak.
      Buckeye is reported to have originated in California as a limb sport of Washington.  It was introduced in 1903 by the R. M. Teague Nurseries of San Dimas.  This weak-growing and chimeric variety has never attained much commercial importance.

Carter
      Both the tree and fruit of this California variety are so similar to Washington that they are indistinguishable.  Grown under the same conditions, however, the rind of Carter appears to be somewhat smoother and thinner, the flesh texture a little less firm and juicier, and the flavor somewhat sweeter (less tart).  Carter is also slightly earlier in maturity.
      Presumed to be a bud variation of unknown origin, a number of old trees of this variety were noted about 1925 in the A. N. Carter orchard at Sierra Madre, California.  The variety was introduced by the Armstrong Nurseries of Ontario, California in 1928 and recommended for home planting.  It is still in demand in California and has been planted to some extent elsewhere.

Company
      Fruit medium-small to medium, subglobose to oblate; basal end deeply furrowed; apical end drawn out to a broad point in which a prominent navel is embedded.  Flesh melting, juicy; flavor good, but acid until late in the season.  Midseason in maturity (much later than Washington).
      Tree vigorous, large, and productive, but with tendency to alternate bearing.
      The Company variety is a South African selection of the so-called Australian navel made in one of the orchards of the Webster Estates at White River in 1913.  While this variety has not been planted for many years, old orchards of it still exist in the White River area.

Dream
      Fruit medium-sized, subglobose to spherical; navel medium to medium-large; rind smooth, well-colored, and of medium thickness.  Flesh texture moderately soft; flavor rich and sweet (less acid than most navels).  Early in maturity and in Florida holds on tree better than most navels without loss of internal quality.
      This Florida variety was found in 1939 by D. J. Nicholson of Orlando as a budded tree in an old orchard of mixed varieties near Sanford.  It was named, patented (U.S. Plant Patent No. 625), and released in 1944.

Dungan
      See under Thomson.

Flannagan (Baddaford)
      This South African selection is from an individual tree in the Flannagan orchard at Baddaford, Fort Beaufort, eastern Cape Province, planted about 1903, that was much used in the early period of the industry.  There is reason for believing that it was propagated from a Bahia navel tree imported from Brazil and presented to Mr. Flannagan in 1905 by C. P. Lounsbury, government entomologist.  Flannagan is typical of Washington navel in all respects except that the twig growth is perhaps a little finer and thinner.
      A few commercial orchards still exist in the Rustenburg area but new plantings have not been made for many years.

Glen (Glen Improved)
      Glen is similar to the Washington navel but reported to bear more heavily and consistently under similar conditions in Florida.
      Found as a group of trees of similar behavior in a Washington navel orchard of a W. C. Roe of Winter Haven, Florida, this variety is thought to have originated as an unrecognized limb sport.  The possibility would seem to exist, however, that it represents a clonal selection.  It was named and introduced in 1934 by the Glen St. Mary Nurseries of Glen St. Mary, Florida.

Golden Buckeye
      See under Buckeye.

Greathead
      This South African clonal selection was made from one of five trees in the 16-year-old Washington navel orchard of P. Greathead near Nelspruit, eastern Cape Province, that were provided by the U.S. Department of Agriculture in 1919.  The tree selected is said to have been received under the label Shamel.  It is typical of Washington navel in all respects and has been widely used in South Africa.

Navelate (Navel Tardia)
      Fruit similar to Washington but somewhat paler in color; navel less prominent and more commonly closed; rind thinner and more leathery; flesh less firm and juicier; flavor less sprightly.  Matures two to three weeks later than Washington and holds on tree considerably better and later without loss of quality.
      Tree somewhat more vigorous and productive.
      According to Gonzalez-Sicilia, this Spanish variety originated as a limb sport in a Washington navel orchard planted in 1930 in the Vinaroz district of Castellón de la Plana Province.  It was discovered in 1948 by D. Adrian Gil, nurseryman of Alcanar, Taragona Province, who propagated it in 1952 and released it in 1957.  In view of its many desirable features, Navelate is considered to be highly promising.¹¹  Cliapot, however, questions its value and reports that in Morocco the fruit is less juicy than Washington and is not signficantly later in maturity.¹²

Navelencia
      Fruit paler in color than Washington; rind much smoother (similar to Thomson), and slightly tougher; navel somewhat prominent but usually closed.  Maturity slightly earlier than Washington, but later than Thomson.  Flesh texture firm, but juicier than Thomson; flavor as good or better.  Fruit holds better on tree than Thomson.
      Tree less vigorous than Washington.
      This variety originated in the orchard of A. C. Thomson at Duarte, California, and was introduced in 1903 by the R. M. Teague Nurseries of San Dimas.  Although popular for a while, Navelencia has not been planted for many years.

Navel Tardia
      See under Navelate.

Newhall
      Fruit slightly smaller than Washington, oblong to ellipsoid; color reddish-orange (deeper than Washington); flavor excellent; maturity earlier than Washington.
      Tree somewhat less vigorous than Washington and leaves slightly darker green.
      This new California variety is said to have originated as a limb sport in the Duarte area that was propagated by Paul Hackney of the Newhall Land and Water Company of Piru and came to prominence in their variety collection.  Because of its attractive appearance and early maturity, Newhall is currently under trial in several districts of California.

Nugget (Golden Nugget)
      Fruit medium-large, oblong; naval medium small but open; rind relatively smooth and pale yellowish-orange; flesh crisp and moderately juicy; pronounced tendency to splitting.  Early in maturity.
      Tree weak-growing, small, and drooping.
      A limb sport discovered by J. P. Engelhart of Glendora and introduced by the San Dimas Nursery Company in 1893, this Californian variety never attained commercial importance.

Orange Double
      See under Bourouhaine.

Orange du Bey
      See under Bourouhaine.

Pretoria
      Fruit medium-small to medium, subglobose to almost oblate, navel small and inconspicuous.  Flesh juicy, melting, and acid in flavor until late in the season.  Early midseason in maturity (much later than Washington).
      Tree vigorous, large, and productive, but with tendency to alternate bearing.
      Pretoria is a South African selection of the so-called Australian navel type made in 1933 from a distinctive high-yielding tree in the orchard of a Mr. Van Skalkwyk in the Pretoria District.

Riverside (Riverside Early)
      Both the tree and fruit of this Californian variety are very similar to the Washington navel but the rind surface is a little smoother and the percentage of closed navels is higher.  The season of maturity is about the same and possibly slightly earlier for Riverside.
      The origin of this variety is obscure, but it is known that it was sent from California to F. W. Savage at Eustis, Florida, in 1895.  It has never achieved commercial importance in either state.  In a small trial in the Imperial Valley of California some years ago, however, its yield was superior to that of other navel orange varieties including Washington, which suggests June drop resistance.

Rustenburg
      Fruit similar to Washington navel, but more globose; rind thinner, firmer, and smoother; navel less conspicuous.  Slightly later maturity and of good quality.
      Tree not distinctive and bears well.
      This South African variety originated in a group of five variant trees in the orchard of A. P. M. Robinson, Heks Kranz, Rustenburg, and is doubtless a budsport of local origin.  It was first propagated in 1944 and still has limited commercial importance in the Rustenburg area.

Summerfield
      Fruit similar to Washington navel but somewhat smaller, with smaller navel.  Flavor sweet but not rich because of low acidity which results in early maturity.
      Tree reported to be regularly productive in Florida.
      The origin of this Florida variety has been traced to a "selected tree or trees" found in 1928 by W. J. Lyles in an old orchard, locally called the Wild Grove near Weirsdale.  The variety was released by the Summerfield Nursery Company, Weirsdale, about 1931.  It is currently the navel orange variety most widely planted in Florida.

Summernavel (Workman)
      Fruit similar to Washington, but rind thicker and rougher in texture; colors and matures considerably later.  Holds on tree especially well with little loss in internal quality.
      Tree more vigorous, low and spreading; leaves larger than Washington; twig bark distinctively russet-brown.
      A budsport discovered about 1934 in the orchard of J. A. Workman at Riverside, California, this variety was named, patented (U.S. Plant Patent No. 347), and introduced by the Armstrong Nurseries of Ontario in 1942.  Summernavel is recommended for home planting and has not achieved commercial importance.

Surprise
      Fruit very similar to Washington, but averages slightly smaller; rind somewhat smoother; navel for most part closed.  Slightly later in maturity.
      Tree perhaps slightly less vigorous than Washington.
      This comparatively old variety of unknown Californian origin was named and introduced by E. S. Hubbard of Federal Point, Florida, who discovered it in a lot of King mandarin trees propagated from budwood obtained from California after the Florida freeze of 1894-95.  While it fruited much better than Washington, it was never extensively planted in Florida and is virtually unknown in California.  In the opinion of the writer, the possibility exists that Surprise and Riverside are the same.

Suzuki
      Fruit similar to Washington navel in size; navel smaller; rind thinner, smoother, and somewhat deeper color; flavor less acid.  Slightly earlier in maturity but stores well.
      Tree a prolific bearer.
      This Japanese variety was first noted about 1935 as a limb sport in a 20-year-old tree in the orchard of M. Suzuki, in Shizuoka Prefecture, and was released for propagation in 1949 and registered in 1963.  Because it is prolific, very early maturing, and of excellent quality, Suzuki is considered to be very promising.
      Suzuki is one of a number of mutant varieties that Washington navel has given rise to in Japan.  This variety, Tange, and Ukumori are considered the most promising, although navel plantings are currently of minor importance in Japan (approximately 1,750 acres in 1961).¹³

Tange
      Fruit similar to Washington, but somewhat smaller; navel much smaller.  Flavor as good or better, maturity season about the same, and keeping quality somewhat better.
      Tree notably vigorous; flowers very large; leaves broad and thick, with strongly winged petioles; prolific.
      This Japanese variety was found in 1946 as a limb sport in the 25-year-old orchard of H. Tange, in Hiroshima Prefecture, and registered in 1961.  Tange is considered to be one of the most promising navel varieties in Japan.

Texas
      Both the tree and fruit of this variety are similar to the Washington navel, but the fruit of Texas is somewhat smaller, seedier, and exhibits a higher percentage of open navels.  When grown in California, the Texas variety has proven less fruitful.
      Texas was introduced into the United States from Brazil by the U.S. Department of Agriculture in 1916 (Dorset, Shamel, and Popenoe, 1917) and first propagated in 1924 at the Weslaco Substation of the Texas Agricultural Experiment Station.  Early trials there suggested the possibility of greater productivity than Washington and a superiority in fruit quality.  Similar comparisons at the Citrus Research Center in Riverside, California, and at Indio, California, failed to confirm such results as did later trials in Texas.

Ukumori
      Fruit similar to Washington but larger (sometimes much larger); rind thicker and rougher; surface texture coarse; flavor less attractive.
      Tree similar to Washington, but more vigorous and productive.
      This Japanese variety originated as a limb sport found in 1938 in the orchard of M. Ukumori, in Ehime Prefecture, and was registered in 1950.  Because of its fruitfulness and large size, it has been planted to some extent in Japan, but the inferior quality of the fruit seems likely to lead to its replacement with better varieties.

Watt (Watt's Early)
      Similar to Washington but fruit smaller; navel less conspicuous; colors and ripens earlier.  Fruit quality excellent.
      Tree lacking in vigor, small and compact, but precocious and productive.
      This South African variety originated as a limb sport in a Washington navel tree on the property of a Mr. Glegg at Kirkwood, eastern Cape Province, and was noted and propagated by a man named Watt about 1945.  It is currently of little importance and little propagated.

Workmen
      See under Summernavel.

Fruits Resembling the Sweet Orange
      Although some fruits commonly assumed to be natural tangors (mandarin-orange hybrids) exhibit various characters of the sweet orange—adherent rind, solid axis, white cotyledons, and form of the petiole wings—and there are also some that are subglobose in shape and bland in flavor, the writer is unacquainted with any of which the composite picture more resembles the sweet orange than the mandarin and would hence justify their inclusion in a sweet-orange-like group.  This is also true of all synthetic tangors known to him.
      While the Temple, Murcott, and King varieties are usually called oranges in Florida, and the new hybrid Page variety was introduced as an orange, King is regarded in this treatment as a member of the Citrus nobilis mandarin group, Temple is provisionally classed as a natural tangor and the others are included in the Citrus reticulata mandarin group.

SOUR OR BITTER ORANGES (CITRUS AURANTIUM L.)
      Like most of the other citrus fruits of commercial importance, the sour, bitter or Seville orange is considered to have originated in the region of northeastern India and adjoining portions of China and Burma.  Spreading northward to Japan and westward through India to the Mediterranean basin, it finally reached Europe sometime around the Christian era.  The sour orange was among the first citrus to be taken to the New World.  In such climatically favorable portions of the New World as Florida and Paraguay it escaped from cultivation and became feral.  It is the naranja agria or amarga of Spain, melangolo or arancio amaro of Italy, bigarade or orange amére of France, khuskhash of Israel, khatta of West Pakistan and parts of India, and daidai of Japan.
      While the sour and sweet oranges have close resemblances there are important differences which clearly justify their separation into different species.  The sour orange leaf is somewhat darker in color and more taper-pointed and the petiole is longer and more broadly winged.  The fruit is usually flatter and more deeply colored and the rind thicker and more loosely adherent.  The rind surface is generally rougher and is minutely pitted with sunken oil glands.  The core is normally hollow and the flavor sour with pronounced bitterness in both carpellary membranes and albedo.  Most distinctive and easily recognizable differences relate to the odor of the oils in the leaves and rind.  In the sour orange the leaf oil is agreeable and distinctive, whereas in the sweet orange it is merely pleasant.  Sour orange rind oil is strong and somewhat disagreeable in contrast with the sweet and pleasant odor of sweet orange rind oil.  Moreover, the chalazal spot is purple-tinted in the sour orange, reddish-brown in the sweet oranges in general, red in the deeply pigmented blood oranges, and cream-colored in the sugar or acidless oranges (Chapot and Praloran, 1955).
      In comparison with the sweet orange, the sour orange tree is more upright and thorny and much more resistant to such unfavorable environmental conditions as frost, excess soil moisture, and neglect.  However, the sourorange does not attain as large size as the sweet orange.  It is also much more resistant to the widespread gummosis (mal di gomma) disease.  In addition, it is susceptible to verrucosis (scab) and markedly intolerant to the tristeza virus when used as a rootstock, while the sweet orange is highly resistant to both diseases.
      The fruit is too sour and bitter to be acceptable to most palates, although it can be used to make a distinctive and refreshing drink.  Its principal use, however, is in the preparation of a distinctive marmalade, much in demand and appreciated in Europe and especially so in Great Britain, for which sweet orange marmalade is not an acceptable substitute.  To meet this demand, sour oranges are grown to a limited extent in most of the Mediterranean countries.  The principal producing area, however, centers around Seville in southern Spain, where commercial plantings are currently reported at approximately 4,000 acres.  Great Britain comprises the principal sour orange market.  Other products obtained or made from the fruits include rind oil and the liqueurs curaçao and Cointreau.
      Oil of petit grain is distilled from the leaves and young shoots and oil of neroli from the flowers.  For these products, however, which are much used in perfumery, special varieties selected primarily for flower production constitute the principal source of production.  A byproduct of this process is orange flower-water, also used in perfumery, for flavoring cakes, and for medicinal purposes.
      The importance of the sour orange in the citricultural world, however, arises from its use as a rootstock.  Because of its marked resistance to the soil-inhabiting fungi principally involved in the gummosis and foot rot (mal di gomma)diseases, a century or more ago it became the leading rootstock.  While its use as a rootstock has declined greatly in recent years because of marked intolerance to the tristeza virus disease, and it now seems destined to be abandoned for that purpose, sour orange remains a major rootstock in the Mediterranean basin and some other areas.
      Because of the attractive appearance of both tree and fruit and their hardiness and resistance to unfavorable conditions in general, the sour oranges are also useful as ornamentals.
      Three natural groups are distinguishable in the sour oranges, namely the common bitter orange, bittersweet orange, and the variant bitter oranges.

Common Bitter or Sour Orange

      This is the ordinary bitter orange (fig. 4-24) so extensively employed as a rootstock and grown in Spain and elsewhere as a marmalade fruit.
      The principal marmalade variety in Spain (Gonzalez-Sicilia, 1963) is Sevillano (Agrio de Espana, Real), whichis said to consist of a group of selected clones characterized by victor, comparative freedom from thorns, and productivity.
      In California, comparison of rootstock clones from many parts of the citricultural world with some of local origin has revealed a considerable range of variation in both tree and fruit characters but none has proved to be outstandingly superior though several have been named.

Bittersweet Orange

      The bittersweet orange group, which contains at least two varieties, may be regarded as a subgroup of the common bitter orange, from which it differs mainly in lower acidity and better flavor.
      Formerly thought to be a hybrid of the sweet and sour oranges, the weight of evidence suggests that the bittersweet orange originated as a mutation from the latter.  It appears to be identical with thc fruit described by Risso and Poiteau (1818-22, p. 101) as the sweet-fruited bitter orange of the Mediterranean basin.  It seems likely that the Spanish took this orange to both Florida and South America, for it was early found in the former and occurs extensively in Paraguay where it comprises an important source of oil of petit grain.
      Minor differences that characterize most of the bittersweet oranges include somewhat denser and more compact habit of growth, broader and less taper-pointed leaves, and paler-colored fruit of slightly smaller size and smoother rind texture.
      Two named varieties, both of which doubtless consist of more than one clone, are Bittersweet of Florida and Paraguay (Apepu).  They are so similar as to be scarcely distinguishable.

Variant Bitter Oranges

      In contrast with the high degree of similarity that characterizes the common and bittersweet sour oranges, the variant bitter oranges exhibit a remarkable degree of diversity of forms and characters.  All are less vigorous than the common and bittersweet oranges—some strikingly so—and, in general, they have broad, spreading tops, few or no thorns, smaller and less wing-margined leaves, and smaller and flatter fruits containing fewer seeds.  A few exhibit teratological characters of a brachytic nature.  Variant bitter oranges are grown principally for perfumery purposes and as ornamentals.

      Perfumery Varieties (Bouquetiers).—While extensive use is made in Italy and Paraguay (and to some extent in Spain and North Africa) of the flowers of the common bitter orange for production of oil of neroli and the byproduct orange flower-water, special perfumery varieties grown solely or primarily for the flowers are employed in the French Riviera, the traditional perfumery center of the Mediterranean basin, and also in North Africa.  For the most part these varieties are characterized by small tree size, freedom from thorns, and profuse flowering.  The three varieties most widely grown appear to be the following:

Bouquet (Bouquet de Fleurs) (fig. 4-25)
      This heavy-flowering variety constitutes an attractive ornamental in California, lending itself especially well to use as a hedge plant.  In California, it is characterized by small tree size with a spreading top consisting of thornless branchlets with short internodes (brachytic in nature) and dense clustered foliage.  The leaves are small, oval, and round or blunt-pointed with short wingless petioles.  The fruits are small, somewhat oblate, moderately pebbled and well-colored, with medium-thick rind, solid axis, and few seeds.  Chapot (1964a) considers this to be the old most Bigaradier Riche Dépouille of Risso and Poiteau (1818).

Bouquetier a Grandes Fleurs (Bouquetier à Peau Epaisse)
      This variety is much the most important of the perfumery varieties (Chapot, 1946b) and is characterized by very large, single flowers and large round fruits with very thick and hard rinds.  The tree is small and spineless and the leaves are medium-sized, broad and blunt, or round-pointed.  The fruit makes excellent confections.

Bouquetier de Nice a Fleurs Doubles (Bouquetier de Nice à Fruits Plats, Bouquetier de Nice)
      This variety is the Bigaradier à Fruit Fetifere of Risso and Poiteau (1818-22).  The tree is vigorous and upright-growing and the flowers are double with a very large pistil, which usually gives rise to a flat fruit of medium size that is also double, since it contains a well-developed secondary fruit deeply embedded inside the primary fruit.  The leaves are very large and broad but slightly taper-pointed.

      Ornamental Varieties.—Although the perfumery varieties are also used as ornamentals, there are other variant or aberrant forms of the bitter orange that are grown only as ornamentals.  Among these are the following:

Abers Narrow Leaf (fig. 4-26)
      This is an extremely narrow-leafed form, the tree of which is small and drooping in habit and the fruit of which is typical for bitter orange with thc exception that the calyx is fleshy.  The presumption is that Abers Narrow Leaf originated in Florida, where it received its name, though it may have been introduced there.  From the literature, it appears to be very similar to, if not identical with, the Granito variety (salicifolia)of Trabut as described in Algeria.

Kabusu (Kabusudaidai)
      This variety is reported to be virtually indistinguishable from Zadaidai except that the calyx is normal and not large, fleshy, and distinctive.
      Both Zadaidai and Kabusu are grown primarily as ornamentals in Japan and the fruits are used for decorative purposes and in the preparation of marmalade and vinegar.

Kikudaidai (Citrus canaliculata Y. Tanaka)
      The Kikudaidai variety is an attractive, somewhat dwarfed ornamental with fruits that have a solid core and are medium-small, subglobose to oblate, yellowish-orange, and characteristically deeply, longitudinally grooved.  The origin of this ornamental is unknown.

Panaché
      See under Variegated below.

Variegated (Panaché)
      While variegation is not uncommon in citrus fruits, clones are comparatively rare in which it is exhibited in both foliage and fruits combined with good vigor and attractive appearance.  A bitter orange clone which meets these requirements occurred about 1920 as a seedling in a nursery of the Citrus Research Center, Riverside, California.  Since Variegated reproduces from seed to a remarkable degree, it is believed to have originated as a nucellar chimera.
      It is characterized by vigor, though not as great as the seed parent, and the variegation is manifested mainly in the fruits, a high percentage of which are beautifully striped with yellow and deep orange.  It has been propagated under the name Variegated Sour.
      That one or more clones of similar appearance are known in the French Riviera is clear from literature references to the Bigaradier Panaché.

Willowleaf
      As the name indicates, this is a willow-leafed form of ornamental.  The tree is moderately dwarfed, of highly symmetrical round-topped form, with dense compact foliage consisting of small, narrow, sharp-pointed, yellowish-green leaves.  The fruits are small, round to pyriform, yellowish-orange and with only juiceless flesh.
      Only one clone of Willowleaf has been noted in California and its origin and history are unknown (Bitters, 1957), although it is believed to have been introduced under the botanical variety name salicifolia.  It is markedly different from Abers which has sometimes called Willowleaf.

Zadaidai (fig. 4-27)
      The Zadaidai is a well-known variety in Japan.  The tree is somewhat lacking in vigor, usually dwarfed, round-topped, and nearly thornless, but otherwise similar to the common bitter orange except that the leaves are slightly smaller, with petioles more narrowly winged.  The fruit differs only in the fact that the calyx is unusually large, well developed, and very thick and fleshy, a character occasionally found in other citrus fruits.

      Fruits Resembling the Sour Orange.—In parts of the Orient, notably Japan, there are citrusfruits commonly referred to as species which appear to be natural hybrids of sour orange parentage.  Those of commercial importance that resemble the sour orange for the most part also exhibit mandarin characters.  The principal fruits among these are the following:

Kitchli (Vadlapudi and Guntur Sour Orange) [Citrus maderaspatana Tan.] (fig. 4-28)
      Fruit medium-sized, depressed globose to broadly obovoid; sometimes slightly necked; color yellowish-orange; seedy; rind rough, somewhat warty, and of medium thickness and adherence.  Core semi-hollow at maturity.  Flesh pale orange-colored; flavor pleasant at full maturity, with slightly bitter aftertaste and musky aroma.  Prior to maturity flesh sharply acid.  Cotyledons light green.
      An old Indian fruit of unknown origin, the Kitchli somewhat resembles the bittersweet orange though it is smaller, flatter, and rougher in surface texture.  It is of commercial importance in South India, principally in the Guntur district, where it is grown on a somewhat extensive scale.  Several clones are recognized, but only that of mildest flavor is propagated commercially.

Nanshôdaidai [C. taiwanica Tan. & Shimada]
      Fruit medium-large, obovate; broadly necked and narrowly collared; seedy.  Rind medium-thick but easily peeled; somewhat pebbled; prominent sunken oil glands; color lemon-yellow.  Sections 10 to 12 and axis open.  Flesh color dull yellow; juicy; acid flavor with bitter aftertaste.  Seeds large, slimy, with wrinkled seed coat, and polyembryonic.
      Tree vigorous, upright-spreading, and very thorny.  Foliage consists of medium-large, somewhat slender, light green, sharp-pointed, strongly winged leaves, the oil of which is suggestive of bitter orange.
      Thought to have originated in the Nanshô district of Taiwan (Formosa), where it has no economic importance, the Nanshôdaidai is included here because of its promise as a substitute for sour orange rootstock in California.

Naruto (Narutomikan) [C. medioglobosa Tan.]
      Fruit medium-sized, subglobose to slightly oblong; orange-colored; seedy; rind smooth but rather thick; easily removed rind and open core.  Flesh color yellowish-orange; tender and juicy; flavor good.  Very late in maturity.
      A very old Japanese fruit of unknown origin, the Naruto is still grown but no longer propagated.  It is confined to Awaji Island of Hyogo Prefecture.

Sanbô (Sanbôkan) [C. sulcata Takahashi]
      Fruit medium-sized and obovoid; collar or neck prominent; rind medium-thick, yellow, coarsely pebbled, somewhat bumpy, and easily removed, with tendency to re-green.  Flesh moderately juicy and flavor good.  Late maturity.
      Sanbô is an old Japanese fruit of unknown origin, first described in 1848, that is still popular and grown mainly in Wakayama Prefecture.

Myrtle-leaf Orange (Citrus myrtifolia Rafinesque)

      Because it somewhat resembles the sour orange, the myrtle-leaf orange (chinotto of Italy, chinois of France) is commonly considered to be a botanical variety of C. aurantium L.  Indeed, the presumption is that the myrtle-leaf orange originated as a mutation from the sour orange.  The differences are sufficiently great and the degree of variation exhibited so wide, however, as to appear to justify separate species standing.
      The several forms of the myrtle-leaf orange are all characterized by lowvigor, slow growth, and small trees with brachytic thornless branchlets, the internodes of which are so short that the leaves are crowded and the growth habit more or less dense and compact.  The leaves are very small, dark green, and usually but not always lanceolate-pointed.  The fruits are small, oblate to round, with more or less rough rind surface and orange to deep orange in color.  The seed content is highly variable and ranges from few or no seeds to many.
      The myrtle-leaf orange has been known for some centuries in the Mediterranean and, as its Italian and French names imply, was presumably introduced from China.  It is grown primarily as an ornamental though the fruits of certain forms have long been prized and used for candying or "crystallizing" whole.  Its commercial culture appears to be confined largely to the province of Liguria, Italy.  Elsewhere it is an attractive and useful ornamental.
      At least four forms or varieties of myrtle-leaf orange are recognized and there are doubtless several clones of each.  Three of these forms have leaves which resemble those of the myrtle; the leaves of the fourth are more like those of the boxwood.  The varieties are as follows:

Boxwood Leaf Chinotto (Chinois à Fouilles de Buis)
      This form or variety is less dwarfed than any of the other chinottos and is characterized by somewhat larger, oval-shaped and round-pointed leaves that resemble the boxwood rather than the myrtle.  The tree is round-topped and symmetrical with dense, dark-green foliage and is highly ornamental.  The only clone grown in California is unfruitful and it is not known whether fruitful clones exist in the Mediterranean.

Crispifolia Chinotto (Crinkle-Leaf Chinotto)
      This variety, known only in the Mediterranean basin, is reported to be less dwarfed and more upright in growth than any of the other myrtle-leafed forms and is said to be characterized by crinkled or twisted leaves.

Large Chinotto (fig. 4-29)
      This variety resembles the small chinotto (see below), but the plant is less dwarfed and larger and the growth habit less compact.  The leaves are broader and somewhat larger and the flowers less showy.  The large chinotto is highly productive and the fruits are also larger and hang well on the plant, making it ornamental the year round.  The fruit is well adapted to preserving or candying.  Seedless clones have been reported.

Small or Dwarf Chinotto (fig. 4-30)
      This is the smallest of the myrtle-leaf oranges.  The plant is a highly dwarfed thornless tree or shrub with very small, clustered, myrtle-like leaves and a compact, symmetrical, round to broadly conical form.  It blossoms profusely but varies greatly in fruitfulness.  Some clones bear very little but others are highly productive.  The fruit hangs until picked so the appearance is that of everbearing.

Bergamot (Citrus bergamia Risso)

      While the distinctive fruit of the bergamot (bergamotto of Italy, bergamote of France) is sometimes referred to as an orange, its resemblances to the oranges are so remote or lacking that it seems best to employ the European usage.  Both the origin of the name and its significance are obscure.  It appears to be a hybrid of the sour orange, however, for which reason it has commonly been regarded as a botanical variety of C. aurantium L.  Since the differences are numerous and marked and a wide degree of variation is exhibited, separate species standing seems to be justified.
      The tree is moderately vigorous, upright to spreading in habit, virtually thornless, and with new shoot growth not pink- or purple-tinted.  At full maturity it is medium-small to medium in size.  The leaves are large and somewhat like the lemon in color, form, and emargination, although the blades are sharper-pointed and the petioles are longer and more broadly winged.
      The flower buds and flowers are medium-large and pure white and there is but one bloom.  The lemon-yellow-colored fruits are small to medium-large, oblate, round obovate or broadly pyriform, frequently possess a small navel, and usually have a persistent style.  The rind is medium-thin with a smooth to moderately rough surface, commonly ridged, and adherent.  The segments are numerous and the core solid.  The flesh is moderately firm, pale greenish-yellow, and highly acid with a faint bitter aftertaste.  The highly monoembryonic seeds, comparatively few and sometimes none, often are not well developed.  The cotyledons are white or faintly green.
      A distinctive characteristic of both foliage and fruits is the strongly pungent and agreeably aromatic oil, which is similar to that of the sour orange leaf, though the rind oil of the latter is different.
      The bergamot has been known in the Mediterranean for several centuries, the distinctive and desirable characteristics of its oil having been recognized as early as 1750.  Two kinds were described by Volckamer (1708-14, p. 155) and five by Risso and Poiteau (1818-22).  Presumably it originated as a seedling in southern Italy.  While there is general agreement that the sour orange has one parent, the other parent is a matter of conjecture.  It has usually been assumed that it was the lemon, but Chapot (1962b) has presented rather convincing evidence in support of the conclusion that some kind of acid lime was the other parent.  In this connection, it may be of interest to note that the distinctive aroma of bergamot oil occurs also in the limettas (C. limetta Risso) of the Mediterranean basin, which are sometimes incorrectly referred to as bergamots.
      For reasons that are not clear, the commercial culture of this fruit, which is grown primarily for the rind oil, is virtually confined to the province of Calabria in southern Italy, where the most recent statistics indicate a total planting of approximately 7,500 acres.  While the tree grows and bears well in Sicily and in portions of North Africa and elsewhere, reportedly the oil is highly variable, inferior in quality, and therefore unprofitable.
      Bergamot oil is commercially important because it constitutes the base of cologne water (eau de cologne), perhaps the most widely used toilet water, and also has other perfumery uses.  According to Chapot (1962b), this cologne water was developed in Cologne in 1676 by an Italian emigrant, Paolo Feminis, and commercialized by his son-in-law, Gian Maria Farina.  Its manufacture dates back to 1709.  Bergamot petit grain oil is another product, of minor importance, distilled from the leaves and young growth.  An important byproduct of the highly acid juice in the oil extraction process is citrate of lime or citric acid.

      Varieties. —Several forms or varieties of bergamot are recognized, among which are the common Bergamot, Melarosa, Torulosa, and Piccola.
      The common bergamot (bergamotto of Italy) appears to consist of two clones which are often confused with each other and, in fact, frequently overlap in characteristics: Femminello (note also the lemon variety of the same name) and Castagnaro.  The two clones are listed separately with other varieties below and their principal differences are as noted by Chapot (1962b).

Castagnaro (fig. 4-31)
      The tree is more vigorous and upright and attains larger size than the Femminello but is somewhat less fruitful.  The fruit is prevailingly round and sometimes slightly ribbed, but frequently exhibits a short neck and obovate form.  The rind surface is commonly rougher and the oil is usually somewhat less aromatic than Femminello.

Femminello
      The tree is somewhat less vigorous and smaller than Castagnaro but earlier and more regular in bearing.  Thefruit is spherical or nearly so, the rind smooth, and the oil somewhat more aromatic and hence preferred.
      Femminello is considered to be the best bergamot variety and Chapot (1962b) concludes that it represents a superior selection of Castagnaro.
      Femminello and Castagnaro are the two markedly preferred varieties of bergamot and constitute virtually all of the commercial production.

Melarosa
      The Melarosa variety is distinguished by theform of the fruit, which is flat to decidedly oblate and sometimes has a small, apical mammilla.  It is of minor and local importance only.

Petite
      See under Piccola below.

Piccola (Petite)
      This form was described by Risso and Poiteau (1818-22) and while mentioned in subsequent literature is unknown to the writer or to Chapot (1962b).  If Piccola were a true bergamot, it seems to have disappeared.  More probable, however, is thelikelihood that it represents a variant seedling clone or that the name was erroneously used for one of the dwarf perfumery varieties of the sour orange, such as Bouquet.

Torulosa (Striata)
      This variety is also characterized by the fruit, which is somewhat larger than Melarosa and broadly pyriform or obovoid.  Its most distinctive feature, however, consists in the numerous, small, longitudinal and darker-colored ridges in the rind which give it a striated or striped appearance.  The peel also averages thinner than in the other bergamots.
      Torulosa has no commercial importance.

THE MANDARlNS
      Principal in importance in the Orient are the mandarins, a large, distinctive, and highly varied group that includes some of the finest and most highly reputed citrus fruits.  Closer in resemblance to the oranges than to any of the other groups, these fruits are commonly referred to as mandarin or loose-skin oranges—a usage which is both unfortunate and confusing in view of the numerous, highly distinctive differences between the two groups.  In the United States, where the name tangerine first came into common usage, mandarin and tangerine are used more or less interchangeably to designate the whole group.  Since mandarin is the older and much more widely employed name, its use is clearly preferable.  Presumably because of the orange-red color of the Dancy variety, which originated in Florida and was introduced in the markets as the Dancy tangerine, horticulturists have tended to restrict the use of the term tangerine to the mandarins of similar deep color.  However, this is a usage of convenience only and the tangerines do not comprise a group of natural significance.  The mandarin is the mikan of Japan, the suntara or sangtra (numerous modifications) of India, the mandarino of Italy and Spain, and the mandarine of French-speaking countries.
      While the range of variation in characters exhibited by the mandarin group is much greater than in the oranges or pummelos and grapefruits and the existence of a number of species is indicated, the distinctive features of the group as a whole are as follows:
      Fruit very small to medium (prevailingly smaller than the oranges), oblate to highly compressed form; rind and fruit sections loosely adherent (more so than any of the oranges); open core (much more so than any of the oranges); flavor and aroma commonly distinctive; seeds with greenish cotyledons (minor exceptions).
      Tree very cold-resistant (more so than any of the oranges) but fruit not; distinctive leaf petioles (wings line-margined with few exceptions); blade notch-pointed and with main vein prominent above as well as below; spines small and few or lacking; flowers single or in unbranched inflorescences and prevailingly small (minor exceptions).
      That the mandarin probably originated in northeastern India is strongly suggested by the existence in the forests of Assam of a primitive form, Citrus indica Tan., the so-called Indian wild mandarin, together with numerous mandarin hybrids and other and more highly developed forms not found elsewhere.  It seems clear, however, that the King and Kunenbo mandarins must have originated in Indo-China and it is virtually certain that the satsuma mandarin had its origin in Japan.  South China must also be the region of origin of some of the numerous mandarins.  Finally, there is considerable reason for concluding that the Mediterranean mandarin, as the name indicates, originated under cultivation in Europe, presumably in Italy.
      According to Webber (1943), the first mention of the mandarin in Europe relates to the introduction into England by Sir Abraham Hume in 1805 of two mandarins from Canton, China, one of which was described and illustrated in 1817 in the Botanical Register and the other in 1824 in Andrews Botanical Repository.  Ziegler and Wolfe (1961) have concluded that one of these introductions was the highly reputed ponkan.  That the mandarin had reached the Mediterranean basin somewhat earlier seems likely, however, for Risso and Poiteau (1818-22) mention a "mandarin orange" which had been known there "for some years" and Chapot (1962c) assigns the date of origin of the Mediterranean mandarin as between 1810 and 1815.  From the fact that in 1830 the village of Monroe on the St. Johns River in Florida changed its name to Mandarin, Ziegler and Wolfe (1961) concluded that this fruit must have been introduced into the United States about 1825.  The fates of that introduction and of another known to have been made in 1838 are obscure.  The first known successful introduction is said to have been made by the Italian consul at New Orleans between 1840 and 1850 and consisted of the Mediterranean mandarin, which came to be known as Willowleaf in this country (sometimes erroneously called China).
      In general, mandarin trees are the most cold-resistant of the citrus fruits of commercial importance, although some of the hybrids, notably the Temple variety of Florida, are striking exceptions.  So far as is presently known, the satsuma mandarins are the hardiest and the King and kunenbo group the tenderest.  Primarily because of the small size and thin rind of the fruit, however, the mandarins are more subject to cold damage than the oranges or grapefruit.  Likewise, the mandarins are among the most heat-resistant of citrus fruits, comparing favorably with the grapefruit, although exposed fruits may become sunburned.  The mandarins, therefore, have a wider range of climatic adaptation than any other citrus group.  They also exhibit a wider range in total heat requirement and hence season of maturity.  Thus, under comparable conditions, the earliest satsuma mandarins attain horticultural maturity earlier in the fall than any of the oranges or grapefruits, and the King mandarin and some others ripen the following spring or early summer fully as late or later than the latest oranges or grapefruit.  It should be noted, however, that the development of good flavor seems to require a period of relatively hot weather during the latter part of the growing season.  Some of the mandarins, notably the Dancy variety, appear to have a lower chilling requirement for good color development than do the oranges in general, since they color better in semitropical and tropical climates.  Under similar conditions, however, satsuma mandarins are especially slow in color development and commonly attain horticultural maturity while still poorly colored.  For reasons that remain obscure, this fruit is climatically better adapted than the oranges to the monsoon regions of the Orient, where mandarin culture is highly important.
      Environmental influences on mandarin fruit characteristics are especially pronounced and important.  Fruit size is markedly enhanced by beat and high atmospheric humidity.  Fruit form is materially and unfavorably affected by low atmospheric humidity, which causes the axis to lengthen and the shape to become rounder and less oblate.  In addition, the tendency to development of a neck, present in most mandarins, is accentuated.  As a consequence, the form may change from oblate to pyriform.  Such effects are most pronounced on some of the tangelos and the differences between desert-grown and coastal fruits of the same variety in California may be so marked as to be scarcely credible.  Both composition and flavor also are markedly influenced by climatic factors.  In hot, humid climates the fruit is juicier and milder in flavor because of lower acid content.  Moreover, the effects of rootstocks on these and other characteristics of the fruit may be even more pronounced and highly unfavorable.  Thus, the rough lemon rootstock so markedly affects the composition of certain mandarins that they are insipid in flavor.  In addition, it materially shortens the period they can be held on the trees without loss of quality from granulation.  These effects seem to be accentuated on light-textured soils, and vice versa.  In this connection it should be remarked, however, that certain rootstocks, notably trifoliate orange and sour orange, enhance the quality of most mandarins and extend the period of its retention in the fruit while still on the tree.  Among varieties most sensitive to such influences is Temple in Florida.
      The above-mentioned climatic tolerances, requirements, and influences serve to explain why commercial mandarin culture in the United States has developed primarily in Florida and elsewhere is restricted to the hottest portions of California and Arizona, where it still may be regarded as somewhat experimental,
      The production problems and practices most distinctive to commercial culture of the mandarins and their hybrids—in particular the tangelos—appear to be concerned with bearing behavior and fruit size.  Some of the mandarins—notably the Mediterranean mandarin and its hybrids, and Dancy also to some degree—exhibit a pronounced tendency to alternate bearing in which the large crops consist of undesirably small, unmarketable fruits.  Not uncommonly, excessively large crops result in little or no bloom the following season.  Thus far, attempts to regulate bearing behavior and control fruit size to some degree have been comparatively unsuccessful, although fruit-thinning accomplished byspring pruning in the heavy crop years has been reported to be helpful and is sometimes practiced.  Chemical fruit-thinning sprays have shown promise, particularly on mandarins; they are thus far limited in effectiveness because of difficulty in predicting the degree of thinning.
      While most citrus fruits are strongly parthenocarpic and require neither pollination nor seed formation for fruitfulness, this is not the case with certain mandarins—particularly the standard Clementine and the Orlando and Minneola tangelos.  The presence of seed is requisite to fruitfulness for those mandarins and can be assured only by cross-pollination, since they are partially self-incompatible.  While limb girdling has been reported helpful for the Clementine in Morocco, it would appear safest to interplant with suitable pollinators.
      Among the fruit-handling problems encountered in mandarin culture are the comparative shortness of the fresh-fruit season and the sensitivity of fruit to injury during handling operations.  With only a few exceptions, the "on-tree" life of ripe mandarin fruits with retention of satisfactory quality is restricted to a few weeks, after which the rind "puffs" and both juice and acidity diminish rapidly.  If fruit is picked at the right stage and kept in cold storage, however, the marketing season may be extended by several months.  The availability of storage facilities, therefore, has special importance in the handling of most mandarins and particularly such early ripening kinds as the satsumas.  Because of their thin, comparatively soft, loose rinds the mandarins are the most delicate of citrus fruits and even with the greatest care in all fruit-handling operations waste losses are still often considerable.
      As a result, mandarins are comparatively high in production and marketing costs, which are passed on in high prices to the consumer.  Consequently, in the United States and Europe the mandarin remains a luxury or specialty fruit used largely for decorative purposes or in gift packages for holiday season activities.
      Accurate statistics on world mandarin production are not available, but it is highly probable that this fruit was second to the sweet orange in importance in 1965-66 with a production of between 67 and 72 million (70-lb equivalent) boxes, which included 7 million boxes of Temple and tangelos produced in Florida.  Mandarin production is most important in the Orient.  Japan is by far the leader—approximately 36 million boxes in 1965.  Production is high in India and China, but meaningful statistics are not available.  Florida ranks second to Japan with a 1965-66 production of about 5.4 million boxes (70-lb equivalent) of so-called Temple oranges, 4.9 million boxes of tangerines, and 1.5 million boxes of tangelos—a total of nearly 12 million.  Spain, Italy, and Algeria normally produce between 3 and 4 million boxes each, Morocco about 2.5 million, and Argentina, Greece, and Egypt between 1 and 2 million each.  Australia, South Africa, Israel, and Lebanon produce a few hundred thousand boxes each.  The 1965-66 production in California was a proximately 800,000 boxes (75-1b) and will increase appreciably in the near future.
      Mandarin processing is of minor importance except in Japan and Florida.  In 1964-65, about 15 per cent of the satsuma mandarin crop in Japan was processed, the principal products being canned fruit segments and juice.  A significant portion of the Florida production of Dancy tangerines is converted into canned juice.  Elsewhere the principal if not the only market outlet is shipment as fresh fruit.
      In comparison with the oranges, the natural group they most resemble, the mandarins exhibit a wider range of variation in such respects as size, fruit color, rind adherence, flavor, and season of maturity.  While most varieties of commercial importance (the satsumas, Dancy, Nagpur, Mediterranean, and Clementine) are medium-small to medium in size and a few are medium-large to large (King and Ortanique), there are a number of very small-fruited mandarins (Cleopatra and kinokuni) of horticultural value or interest as rootstocks or ornamentals.
      The color range exhibited is very great—from the pale yellowish-orange of the Mediterranean mandarin and some other varieties to the deep orange-red of some of the so-called tangerines such as Dancy.  In this connection, it should be noted that pigmented mandarins, comparable to the blood oranges, apparently do not exist.  The so-called blood mandarin (mandarine sanguine)of Morocco is merely a deep orange-red-colored variety, the flesh of which is completely lacking in pink or red coloration.
      With respect to degree of rind adherence, some of the mandarins (Ellendale, Clementine, and the naartje of South Africa) have rinds that are rather closely adherent—though readily peelable—and remain so even after horticultural maturity in contrast with other varieties (the satsumas, Dancy, and Mediterranean) in which the rind is loosely adherent at maturity and continues to separate thereafter.  The range of variation in flavor and aroma is also great—from bland to rich and fragrant.  So far as the writer has been able to ascertain, however, there are no acidless mandarins comparable to the sugar or acidless oranges.  On the other hand, Swingle (1943) reports there are several small-fruited mandarins (sunkat of South China and others) that are highly acid at maturity and never become edible.  Finally, the length of season during which mandarin varieties attain maturity is somewhat longer, since some of the satsumas ripen earlier than any of the sweet oranges and the King mandarin is fully as late or later than the Valencia orange.
      With respect to seed content, the two groups are similar in that there are seedy, slightly seedy, and seedless varieties in both.  However, there are many more orange varieties of low seed content, since most mandarin varieties are comparatively seedy.  An interesting parallel may be noted in the fact that the satsuma mandarins and navel oranges are both seedless and for the same reasons viable pollen is not produced and functional ovules are exceedingly few.  While navel varieties of the mandarin are not known, the satsuma group exhibits a marked tendency to develop small navel-like structures.  Certain other mandarins possess this tendency, but less markedly.

Natural Groups
      Although obviously closely related, the mandarins are clearly separable into several natural groups.  Their classification into three species by the American authority Swingle (1943) seems untenable, especially in view of the fact that the Japanese systematist Tanaka (1954) has recognized 36 species of mandarins.  Tanaka's classification, which clearly is the most comprehensive treatment undertaken thus far, places the mandarins in the following five taxonomic groups:
    I. Section Acrumen—Subsection Euacrumen.
       Characterized by large flowers, leaves, and fruits.
       Three species: nobilis, unshiu, and yatsushiro.
  II. Section Acrumen—Subsection Microacrumen—Group Anisodora.
      A distinctive small-fruited, yellow-colored group from the Okinawa and Luchu islands.
      Three species: keraji, oto, and tarogayo.
III. Section Acrumen—Subsection Microacrumen—Group Citriodora—Subgroup Megacarpa.
      Characterized by small flowers and leaves and medium to medium-large fruits.
      Fourteen species: reticulata, deliciosa, tangerina, clementina, suhuiensis, subcompressa, paratangerina, crenatifolia, benikoji, suavissima, tardiferax,
      genshokan, platymamma, and succosa.
IV. Section Acrumen—Subsection Microacrumen—Group Citriodora—Subgroup Microcarpa—Subsection Augustifolia.
      Characterized by small flowers, small but narrow leaves, and small fruits.
      Ten species: tachibana, kinokuni, sunki, reshni, indica, erythrosa, ponki, oleocarpa, pseudo-sunki, and tardiva.
 V. Section Acrumen—Subsection Microacrumen—Group Citriodora—Subgroup Microcarpa—Microgroup Latifolia.
      Characterized by small flowers, small but broad leaves, and small fruits.
      Six species: depressa, amblycarpa, leiocarpa, tumida, lycoperaeformis, and hainanensis.
      Of these thirty-six species Swingle recognized only tachibana and indica, wild species of Japan and India, respectively, and reticulata in which he placed all others.  While the validity of some of Tanaka's species may be questioned, in the opinion of the writer some of them are soundly based.  Although the writer has seen two-thirds of the species in question, his competence is limited to only a quarter of them and, unfortunately, to only four of the fourteen of Group III, which is characterized by small flowers and leaves but medium to medium-large fruits and hence has contributed numerous varieties of economic importance.  As a consequence, but with hesitation and reluctance, the writer has tentatively grouped all but one of them (deliciosa) with reticulata.
      In the presentation which follows, the varieties of principal importance or promise are grouped, therefore, into four species: unshiu, nobilis, deliciosa, and reticulata.

Satsuma Mandarin (Citrus unshiu Marcovitch)

      This mandarin is the famous and highly important Unshû mikan (Unshiu)of Japan.  The name satsuma, by which it has become known in the Occident, is credited to the wife of a United States minister to Japan, General Van Valkenberg, who sent trees of it home in 1878.  Satsuma is the name of a former province, now Kagoshima Prefecture, on the southern tip of Kyushu Island, where it is believed to have originated.  This mandarin may be described as follows:
      Fruit medium-small to medium, oblate to subglobose; sometimes slightly necked; seedless.  Orange-colored but commonly matures prior to development of good color.  Areole faint or indistinct and small; navel frequently present.  Rind thin, somewhat leathery; surface moderately smooth and with large and prominent oil glands; easily separable.  As the fruit passes through maturity, rind surface becomes increasingly bumpy and likewise its separation increases somewhat.  Segments 10 to 12, with tough carpellary membranes, loosely separable; axis hollow.  Flesh orange-colored; tender and melting; flavor rich but subacid.  Pulp-vesicles short and broad.  Season of maturity very early to medium early (includes the earliest-known mandarin varieties).  Fruit holds poorly on trees after maturity and must be picked promptly, but stores well.  The occasional seeds found have light green cotyledons.
      Tree slow-growing, small to medium-small, usually spreading and drooping, nearly thornless; foliage open.  Leaves dark green, large, long, lanceolate, and tapering at base and apex, the latter usually taper-pointed.  Both main and primary lateral veins prominent above as well as below.  Petiole slender, very long, and wing-margined.  Tree very hardy to cold and resistant to unfavorable conditions.
      The highly distinctive satsuma mandarin is considered to have originated in Japan sometime prior to 1600 A.D., the approximate period of the earliest known reference to it.  Since it has never been found in China and its Japanese name Unshû is considered to be a corruption of Wenchow, an ancient province of China, it seems likely that it originated as a chance seedling from a fruit or form imported from that country, probably from Wenchow Province.  According to Ziegler and Wolfe (1961), the first recorded introduction into the United States (Florida) was by George R. Hall in 1876.  The satsuma reached California not long thereafter and within a few decades was established in collections in the Mediterranean basin and elsewhere.
      The satsuma mandarin tree is the most cold-tolerant of citrus fruits of commercial importance, mature dormant trees having survived minimum temperatures of 15º F to 18º F in northern California and southern Alabama without serious injury.  Moreover, because of its apparent low total heat requirement, some varieties ripen earlier than any of the oranges or other mandarins.  However, warm weather is required during the growing season for the development of satisfactory quality.  As a consequence, the satsuma is adapted to regions of winters too cold for other citrus fruits and with growing seasons sufficiently warm to produce fruit of early maturity and good quality.  For reasons that remain obscure, this mandarin has not proven commercially successful in the milder and hotter portions of the subtropics or in the tropics.  Its range of climatic adaptation for commercial culture is therefore narrow and restricted to the upper and colder portions of the subtropical zones.
      In the United States, climatic conditions suitable for satsuma mandarin culture occur in parts of northwestern Florida, in a narrow strip extending along the Gulf of Mexico across Alabama, Mississippi, and Louisiana into eastern Texas, and in the thermal belt of the Sacramento-San Joaquin Valley basin of California.  Some decades ago, there existed in the Gulf Coast region what appeared to be a thriving and promising young industry of some thousands of acres.  Primarily because of a series of unprecedented vicissitudes—introduction of the citrus canker disease and necessity for its eradication and recurrent devastating freezes—those plantings have virtually disappeared.  Replacements currently comprise only a fraction of the original acreage.  At about the same time, small plantings were made in the Sacramento Valley of California which persisted for several decades but ultimately were removed or largely replaced with other varieties, primarily because of handling and marketing difficulties and possibly rootstock-scion incompatibility problems involving virus diseases.  In recent years, however, there has been a revival of interest in this mandarin and about 1,500 acres have been planted, principally in the San Joaquin Valley.
      In portions of southern Japan, climatic conditions are favorable to the production of early ripening satsuma mandarins of high quality and maximum size, which has permitted the development of the world's largest and most important mandarin industry.  The total planting in Japan for 1963 was reported to be 215,000 acres with a production of about 28 million 70-lb box equivalents.  The areas of production are widely distributed, involving the islands of Honshu, Shikoku, and Kyushu and nineteen prefectures (chap. 2, table 2-69, p. 142 [text version, Revised Ed.]).  At the present time, satsuma mandarins comprise about 80 per cent of the citrus acreage and account for approximately a third of the total fruit tonnage harvested in Japan.
      While this fruit is grown primarily for fresh consumption, a significant and increasing portion of the crop is canned as fruit segments or juice.  Limited quantities of fresh fruit have been exported to Canada, where they have comprised the earliest new-crop citrus fruits to reach the markets.  Export of canned fruit segments has increased greatly in recent years and this excellent product is now found in both American and European markets.
      The most unusual or distinctive features of the Japanese industry are as follows: (1) much the greater part of the orchards are close-planted and are situated on relatively steep, bench-terraced slopes; (2) the rootstocks used are trifoliate orange (Poncirus trifoliata [L.] Raf.) and Yuzu (C. junos Siebold), mainly the former; (3) a common and recommended practice is inarching trees on trifoliate rootstock at 12 to 15 years of age or even older with Yuzu seedlings to offset dwarfing and prolong their productive life; (4) the employment of regular and severe pruning; and (5) the availability of extensive storage facilities which make possible notable extension of the fresh-fruit marketing and processing seasons.
      At the dawn of modern horticulture in Japan, five kinds, groups, or varieties of unshu mikans were recognized, three of the names of which refer to localities or districts, one to season of maturity of the fruit, and the other to antiquity of origin.  These horticultural groups are as follows:
      1. Wase (Early)—All early-ripening clones were placed in this group irrespective of origin, known or otherwise.  Indeed, all varieties of Unshû are classified into two groups—Wase Unshû (earliest to ripen, hence very early) and Unshû (ripening later, but still early).  More recently the latter has been subdivided into the intermediate or midseason varieties—Nakate Unshû—and the late ripening varieties—Futsu Unshû.  Wase itself is therefore not a horticultural variety but constitutes a group of very early ripening varieties, each of which carries its own name.  In general, however, these varieties are distinctively different from the typical Unshû.
      2. Zairai (Native, indigenous, or old)—This group is said to include what are considered to be the oldest clones of unknown parentage or origin.  Thus, Miyagawa, currently the most important of the Wase varieties, is known to have originated as a limb sport in a Zairai tree.  Zairai does not exist as a named variety, however, though Zairai clones as a group are usually seedy and inferior in other respects.  They are reported to have originated mainly in Fukuoka Prefecture of Kyushu Island where the Unshû was early taken from Satsuma Province.
      3. Owari (an old province on Honshu Island, now Aichi Prefecture)—This group, much the most important, represents an old clonal variety which early became popular and predominant in Owari Province and may have originated there, although it is thought to have come from Ikiriki of Nagasaki Prefecture.  Because of its excellence, it spread throughout the country and until approximately 1940 was virtually the only variety planted commercially.  Since World War II, however, the plantings have been restricted largely to derivative varieties known to have originated as bud mutations in Owari trees.  Owari itself seems no longer to be propagated as a clonal variety, though it still comprises the bulk of the production.  As a group it is characterized by good tree vigor and productivity and flat fruit of good quality which, because of the firm consistency of the flesh and tough carpellary membranes, is especially suitable for canning.
      4 and 5. Ikeda and Ikiriki (town or village names in Osaka and Nagasaki Prefectures)—These groups seem also to represent old varieties of local origin no longer propagated, though old plantings still exist—of the former, on Shikoku Island and in nearby Wakayama Prefecture on Honshu Island; of the latter, mainly in Saga and Nagasaki Prefectures of Honshu Island.
      Ikeda is reported to be characterized by small, subglobose, and virtually seedless fruit of mediocre quality and relatively late maturity.  The trees of Ikiriki are said to be small, compact, and not very productive, but the fruit is reported to be seedless and of excellent quality.
      During the period of 1908-1911, approximately a million satsuma trees were imported and planted in the United States.  A few years later, a study of the varieties included in the importations (Scott, 1918; Tanaka, 1918) disclosed that they consisted mainly of the Owari type or variety, although three others—Wase, Ikeda, and Zairai—were also identified and described.  In view of these facts, the authenticity of the Wase and Zairai clones in question is doubtful at least and the clones of Owari and Ikeda should probably be regarded as selections of those varieties.  Fortunately, however, the Owari identified and propagated in the United States appears to be true to type for Silverhill, a seedling clone derived from it inFlorida and considered to be of nucellar origin.  It has been tested in Japan and is among the clones currently recommended for planting there.
      The satsuma mandarins must be regarded as a highly unstable group, for as early as 1932 Tanaka (1932) reported numerous bud variations of which some thirty were named and described.  This list has now been extended to a hundred or more, some of which appear to be identical although of different origin.  Of current importance or promise are the varieties described below, nearly all of which are derivatives of Owari.

     Early (Wase) Varieties.—Since the satsumas are characterized by early fruit maturity, the Wase varieties are very early ripening—late September and October.  As a group the trees are said to be more or less lacking in vigor, slow growing, and dwarfed.  They have moderately dense foliage consisting of relatively small leaves with slender, fairly line-marginated petioles.  The Wase varieties comprise about one-fifth of the total mandarin acreage in Japan.  The descriptions that follow are from M. Nishiura of the Horticultural Research Station at Okitsu, Japan.¹⁴

Aoe (Aoe Wase)
      Aoe is primarily of historical interest.  It is said to be the oldest known and hence, perhaps, the original variety of this early ripening group.  While no longer propagated, it is still important in some of the older districts of Japan.

Iseki (Iseki Wase)
      Iseki is currently confined to Koneshima Island in the sea of Japan, where it is gradually being replaced by the larger-fruited Miyagawa variety.  It is considered to have outstanding eating quality.

Matsuyama (Matsuyama Wase)
      Fruit somewhat more oblate than Miyagawa, the leading Wase variety, but reported to mature slightly earlier.
      Tree also more vigorous.  Tested rather widely and considered to be highly promising.
      Matsuyama originated as a limb sport in an Owari tree on the property of U. Ukumori, at Matsuyama, Ehime Prefecture.  The variety was found about 1935 and registered in 1953.

Miho (Miho Wase)
      Fruit somewhat more oblate than Miyagawa, but higher in sugar, usually lower in acid; and earlier in maturity.
      Tree also more vigorous.  Markedly similar to Okitsu, but fruit from young trees has been slower to color and in some location trees have been somewhat more vigorous.
      The Miho variety originated as a sister nucellar seedling to Okitsu but seems to have the slight differences mentioned above.  It was registered in 1963.

Miyagawa (Miyagawa Wase) (fig. 4-32)
      Fruit large (for satsuma), moderately oblate, with thin and smooth rind.  Seedless.  Juice abundant, sugars and acid well-blended, and quality excellent.  Matures very early and stores well for Wase Unshû.
      Tree more vigorous than most old Wase clones and productive.
      Miyagawa originated as a limb sport in a Zairai tree in Fukuoka Prefecture and was named and introduced by Dr. Tyôzaburô Tanaka in 1923.  It is currently the best known and much the most extensively grown of the Wase varieties.

Okitsu (Okitsu Wase) (fig. 4-33)
      Fruit somewhat more oblate than Miyagawa, but averages higher in sugar content and matures a week or so earlier.  Trees also more vigorous.
      Okitsu originated as a nucellar seedling of Miyagawa from a controlled pollination with Poncirus trifoliata made by Doctors M. Kajiura and T. Iwasaki at the Horticultural Research Station, Okitsu, in 1940.  It was distributed for trial in 1953, registered in 1963, and appears to be highly promising.

     Late (Unshu) Varieties.—The late satsuma varieties ripen in November-December and hence are early to medium-early in their maturity season.

Hayashi (Hayashi Unshû)
      Fruit medium-large; sugars and acid relatively high; keeping quality exceptionally good; otherwise like Sugiyama, the principal variety.  Medium-early in maturity (December).
      Tree very vigorous (for satsuma), productive, and more upright than Sugiyama.
      Hayashi originated as a bud variation of Owari on the property of B. Hayashi in Wakayama Prefecture and was found about 1920 and introduced in 1925.  It is grown primarily as a shipping variety and stores well.

Ishikawa (Ishikawa Unshû) (fig. 4-34)
      Fruit very large (one of the largest); rind finely pitted; sugar and acid both high; keeping quality very good.  Maturity season late for satsumas (mid-December).  Otherwise like most othervarieties.
      Tree vigorous (for satsuma), with large, long, somewhat-drooping branches; leaves larger than most other varieties.
      The Ishikawa variety originated as a bud mutation of Owari in the orchard of K. Ishikawa in Shizuoka Prefecture.  It was noted about 1934 and registered in 1950.  This variety is grown primarily because the fruit is late to mature and stores well.

Nankan No. 4
      Fruit large; sugars high and acid low; early in maturity (November).  Otherwise not distinctive. Tree vigorous and productive.
      Nankan No. 4 originated as a bud variation of Owari on the property of S. Yakushiji in Ehime Prefecture and was introduced about 1925.  It is an early shipping variety in some prefectures.

Owari (Owari Satsuma)
      Fruit medium in size, medium-oblate to subglobose; sometimes slightly necked; seedless.  Orange-colored but commonly matures in advance of good coloration.  Rind thin and leathery; surface smooth to slightly rough; easily separable.  As maturity passes, the neck, if present, increases in size, the rind roughens, and its looseness increases, becoming baggy.  Segments 10 to 12, with tough carpellary membranes; loosely separable; axis hollow.  Flesh orange-colored; tender and melting; flavor rich but subacid.  Season of maturity earl November-December.  Fruit holds poorly on trees after maturity and must be picked promptly but stores well.
      Tree moderately vigorous but slow-growing,; medium-small, spreading and drooping; very productive.
      This variety is of ancient and unknown Japanese origin presumably from the old province of Owari, whence the name.  While still important in the older districts it has largely been displaced by derivative varieties that have arisen from it through bud variation.  What is believed to be true Owari was introduced into the United States more than fifty years ago and, since recent Japanese descriptions of it are not available, the characterizations given here are adapted from Webber (1943).  Two nucellar selections, Silverhill Owari and Frost Owari, have been derived from it in the United States and are currently recommended.  Kara, a variety of some interest in California, is a hybrid between Owari satsuma and King mandarin.  Likewise, the Umatilla tangor of Florida is an Owari satsuma-Ruby blood orange hybrid.

Silverhill (Silverhill Owari)
      Fruit medium insize, slightly more oblate than most; rind relatively thinand smooth; seedless.  Juice abundant; sugars high and acid low (hence verysweet); quality excellent; stores well.  Season of maturity early (November).
      Tree veryvigorous (for satsuma), more upright than most others; productive; markedly cold-resistant.
      Silverhill is a nucellar seedling selection of Owari from a cross made by W. T. Swingle of the U.S. Department of Agriculture in Florida about 1908.  The variety was named and introduced about 1931.  Incollections in California, it is indistinguishable from the Frost Owari derived at the Citrus Research Center, Riverside, California, and almost certainly they are identical.  They constitute what are considered to be the best clones currently available in the United States.
      Silverhill has been tested in Japan, where the above characterization was taken to permit direct comparison with other varieties.  It is recommended for planting in Japan as a promising, early shipping variety of Unshû.
      Another nucellar selection, which so closely resembles Silverhill that it is virtually indistinguishable, is Tanikawa Unshû, which originated as a nucellar seedling in the breeding program of the Horticultural Research Station at Okitsu about 1920 and was named for its originator, T. Tanikawa.  The only differences reported are a somewhat lower average sugar content in the fruit and slightly higher average yield to date.  Like Silverhill, it is recommended as an early shipping variety.

Sugiyama (Sugiyama Unshû) (fig. 4-35)
      Fruit large (for satsuma), oblate; rind relatively thin and smooth; seedless.  Juice abundant; sugars relatively high and acid low;quality excellent.  Early in maturity (November).
      Tree moderately vigorous, spreading, drooping, andproductive.
      Sugiyama originated as a bud variation of Owari in the orchard of J. Sugiyama in Shizuoka Prefecture.  First noted about 1930, it was introduced in 1934.  It is one of the principal shipping varieties and is widely grown.

     Minor Varieties.—Satsuma varieties grown on a limited scale and those which offer promise for the future are described below.

Dobashi-Beni Unshu
      Distinctive only because of its deep orange-red color.  Fruit of good quality, ripening in late November or early December.
      Tree of medium vigor.
      This variety originated as a limb sport of Owari in the orchard of K. Dobashi in Shizuoka Prefecture and was noted about 1940.  In marked contrast is Yamabuki Unshû, which is characterized by yellow rind and flesh.¹⁵

Juman Unshu
      Vigorous-growing, small-leafed, late-ripening (December) variety.  Fruit medium-large; rind surface finely pitted; flavor rich; very good keeping quality.
      The Juman Unshû is considered to be promising as a late shipping and storage variety for the warmer sections of Japan.  It originated as a bud mutation of Owari in the orchard of K. Juman in Kochi Prefecture (Shikoku Island) and was named and registered in 1953.

Nagahashi Unshu
      This variety is very similar to Yonezawa below, but the fruit is not as bright in color and both tree vigor and fruit quality are inferior.  A limb sport of Owari that originated on the place of T. Nagahashi in Shizuoka Prefecture, this variety was noted about 1935.

Yonezawa Unshu
      Very large-fruited, bright-colored, early ripening variety that closely follows the Wase varieties.  Tree vigor somewhat lacking, however, and fruit quality only mediocre.
      This variety originated as a limb sport of Owari on the property of Y. Yonezawa in Shizuoka Prefecture and was named and registered in 1955.

Fruits Resembling the Satsuma

Yatsushiro (Yatsushiro Mikan)
      An older mandarin the fruit of which more closely resembles satsuma than any other, according to Tanaka (1961a), is the Japanese Yatsushiro mikan (C. yatsushiro Tanaka), currently of minor and decreasing importance because of an inability to compete with satsuma.  Although of smaller size and sometimes moderately seedy, the fruit is well-colored, juicy and pleasantly sweet.  The leaves, however, are not satsuma-like and are definitely winged.
      Of ancient Japanese origin, Tanaka (1961a) considers this fruit to have been derived from the small-fruited Kishû mikan (C. kinokuni Tan.).

King Mandarin (Citrus nobilis Loureiro)

      The most widely employed name for this little known and relatively unimportant group derives from the American variety known as King which came from Indo-China (South Vietnam) and closely corresponds with Loureiro's original description of the species nobilis.  In the earlier French literature, it was commonly referred to as the Indo-Chinese or Camboge mandarin.  The Japanese name kunenbo (Kunembo) applies to forms that occur there and in China, Taiwan (Formosa), and Okinawa, which are somewhat different but are considered to belong to this species.
      It appears to be the consensus that the King group originated in Indo-China, whence it spread northward as far as Japan and southward throughout Malaya.  Many of the mandarins currently found in the Malayan region and a few in China appear to be of the nobilis type.  Some of the characters exhibited by this group are orange-like and others are intermediate between that fruit and mandarin, which supports the conclusion that King probably originated as a hybrid between the two and is therefore a natural tangor.
      That there are consistent and possibly significant differences between the Kunenbo (fig. 4-36) and King (fig. 4-37) mandarins has been pointed out recently by Tanaka (1961b), but he still considers them as belonging to the same species.  The principal differences he mentions are the larger size and the thicker tuberculate rind of the King as compared to the thinner and smoother rind of Kunenbo and the shorter, less-strongly-beaked seeds with cream-colored cotyledons of Kunenbo.  To these the writer would add a more acrid rind oil and slightly bitter flesh taste for Kunenbo and a considerably more upright and irregular habit of growth for the King, with leaves that are less mandarin-like in form and appearance.  Several kinds of Kunenbo have been described by Tanaka (1961b), and a number of clones have been reported in Indo-China and Malaya which appear to be similar to the King variety of the United States described below.

King (King of Siam) (fig. 4-37)
      Fruit large (among the largest of the mandarins), oblate to depressed globose; base sometimes short-necked but usually depressed and furrowed; apex flattened or depressed; areole moderately distinct.  Rind thick (very thick for mandarins), moderately adherent but peelable; surface moderately smooth to rough and warty.  Deep yellowish-orange to orange at maturity.  Segments 12 to 14, readily separable; axis large and hollow.  Flesh color deep orange; tender; moderately juicy; flavor rich.  Seeds few to many and cotyledons cream-colored.  Late to very late in maturity and stores well on tree.
      Tree moderately vigorous, upright and open in growth habit, and medium in size, with comparatively few thick, stiff and erect, thornless to moderately thorny branches.  Foliage open and consists of large, dark-green, broadly-lanceolate leaves, the petioles of which are medium in length and narrowly wing-margined and the venation inconspicuous in comparison with most other mandarins.  Very, productive but markedly subject to loss from tree breakage and fruit sunburn.  Tree cold-resistant but less so than most mandarins.
      According to Webber (1943), this variety originated as a seedling from fruits of that name received by H. S. Magee of Riverside, California, in 1880 through the courtesy of the United States Minister to Japan, John A. Bingham, who arranged to have them sent from Saigon, Cochin-China (South Vietnam).  It is stated that Magee, who was a nurseryman, sent both seedlings and budwood to J. C. Stovin of Winter Park, Florida, in 1882.
      Climatically, the most distinctive feature of this variety is its very high heat requirement for the attainment of horticultural maturity and good quality, for which reason it is the latest ripening of the mandarins.  The fruit also is markedly affected by environmental influences, including both rootstock and soil.  Thus, when grown in Florida on sour orange rootstock in the heavier-textured soils, the size is large, rind surface relatively smooth, and the flavor excellent—rich and sprightly.  On rough lemon rootstock in light-textured soils, the rind surface is rough and warty and the flavor much less pronounced.  As a consequence, for satisfactory quality its range of commercial adaptation is quite restricted.  In California, it attains acceptable flavor only in the hottest interior districts and is undesirably rough in rind surface and unattractive in appearance.
      At one time King had considerable importance in Florida, but it is now grown very little commercially.  It is still used in the gift-package trade, however, and for home planting.  It has never achieved importance in California.
      Of horticultural interest in connection with this variety is the fact that several of its hybrids are currently of commercial interest in California and elsewhere, among which are Encore, Honey (not the Murcott of Florida), Kinnow, and Wilking, all of King X Willowleaf parentage, and Kara of Owari satsuma X King parentage (Frost, 1935).
      Several observers have reported similarities between the fruits of King and Campeona, a variety of growing importance in Argentina.  These similarities include size, form, roughness and thickness of rind, white cotyledons, and lateness of maturity.

Mediterranean Mandarin (Citrus deliciosa Tenore)

      This is the common mandarin of the Mediterranean basin which is known by many names, most of them local place names that refer to its origin as native or are synonyms of the word common.  According to Chapot (1962c), among the principal place names are Ba Ahmed (Morocco), Blida, Boufarik and Bougie (Algeria), Bodrum (Turkey), Paterno and Palermo (Italy), Nice and Provence (France), Valencia (Spain), and Setúbal (Portugal).  Synonyms for common or native are commune (French), comun (Spanish), gallego (Portuguese), koina (Greek), yerli (Turkish), and beladi (various spellings) for Arabic.  Other names include Effendi or Yousef Effendi (Egypt and the Near East), Avana or Speciale (Italy), Thorny (Australia), Mexirica or Do Rio (Brazil), and Chino or Amarillo (Mexico).  In the United States, it is known as the Mediterranean or Willowleaf mandarin.
      The excessively numerous names by which this mandarin is known are misleading since they suggest the probable existence of a number of varieties.  Such is not the case, however, for Chapot (1962c) has been unable to find differences between them in collections assembled in Morocco.  Comparisons in California between Baladi (Egypt), Avana (Italy), Comun (Spain), and Ba Ahmed (Morocco) have shown no differences except those to be expected between old and young (seedling) clonal lines.

Mediterranean (Mediterranean Common, Willowleaf) (fig. 4-38)
      Fruit medium in size, moderately oblate, frequently slightly lobed; base sometimes even, but usually with low collared and strongly furrowed neck; apex depressed and commonly slightly wrinkled; areole lacking; small navel-like structure fairly common.  Seeds numerous, small, round, plump, and highly polyembryonic, with light green cotyledons.  Rind thin, not leathery, loosely adherent; surface smooth and glossy with large, deep colored oil glands; color yellowish-orange at maturity.  Segments 10 to 12, very loosely adherent; axis hollow.  Flesh color light orange; tender; juicy; flavor sweet; pleasantly aromatic (distinctive).  Moderately early to early midseason in maturity.  As fruit passes through maturity, rind separation increases sharply and "puffing" takes place, accompanied by marked loss of acidity.  Fruit loses quality unless picked promptly.  Unfortunately, fruit does not store well (in comparison with satsuma).
      Tree slow growing, of medium vigor and size, broad-spreading, and drooping in growth habit; branches fine, willowy, and nearly thornless; leaves small, narrowly lanceolate, and of distinctive appearance.  Tree hardy to cold and resistant to unfavorable conditions, but exhibits strong tendency to alternate bearing.
      In comparison with the other mandarins, the most distinctive characteristics of the Mediterranean mandarin include: (1) the small size and narrow-lanceolate form of the leaves and the special nature and aroma of the oil they contain; (2) the mild and pleasantly aromatic flavor of the juice; (3) the distinctive nature and fragrance of the rind oil; and (4) the plump and almost spherical seeds.  Additional distinctive characteristics not confined to this mandarin are the spreading-drooping habit of growth and the very high degree of seed polyembryony.
      Since this highly distinctive mandarin appears not to have been found in the Orient, it seems likely that it originated in the Mediterranean basin and almost certainly in Italy.  After careful review of the literature, Chapot (1962c) has concluded that it appeared in Italy between 1810 and 1818.  It is reported to have been imported into Egypt from Malta about 1830 and is known to have been in commercial production in Italy by 1840, whence it was taken to Algeria in 1850.  Within a few decades, it spread to all the countries of the Mediterranean basin and Near East and soon attained considerable commercial importance.  It was brought to the United States by the Italian consul at New Orleans and planted in the consulate grounds there sometime between 1840 and 1850, apparently being the first mandarin to reach this country.  Not long thereafter, it was taken to Florida and thence probably to California and elsewhere.
      The parentage and mode of origin of this fruit are not known, but it seems likely that it arose as a chance seedling from a mandarin variety or form of Chinese origin.  Because of certain resemblances, Tanaka (1954, p. 16) has suggested the possibility that the szu-ui-kom, szinkom, or sun-wui-kom (Citrus suhuiensis Tan.) of southern China might be the seed parent, although he insists that the two species are distinct.  As seen by the writer in the collection at the Government Horticultural Research Institute, Saharanpur, India, the latter fruit exhibits numerous and striking similarities to the Mediterranean mandarin, including the habit of growth, appearance, and distinctive flavor and aroma of the fruit.  The leaves, however, are much more broadly lanceolate.
      Because of its high beat requirement, tolerance, and the fact that the fruit is well-shaded, this mandarin is adapted to the hot and dry climates that characterize the Mediterranean basin and Near East.  In general, because of the greater amount of heat, both fruit size and quality are superior in North Africa and the season of maturity earlier than in Italy and Spain.  The Baladi or Yussef Effendi mandarin of Egypt is notable for earliness of maturity, and size, the latter evidently an effect of the humidity resulting from the flooding of the Nile during summer and early fall.  In the heat-deficient coastal region of southern California, the fruit is small, of indifferent quality, and late in maturity.
      Although decreasing in importance because of the substitution of other varieties, notably Clementine, the Mediterranean mandarin currently ranks second to the satsumas of Japan.  While accurate and complete statistics are not available, the 1961 crop was estimated at not less than 11 million 70-lb) box equivalents.  The principal producing countries, ranked in approximate descending order of importance, appear to be Italy and Spain, followed by Algeria, Egypt, Brazil, Greece, and Argentina.  This mandarin is of commercial importance, however, in virtually every citrus-producing country of the Mediterranean basin and the Near East.  Early taken to South America and grown largely as seedling trees, it is the Mexirica do Rio or Do Rio of Brazil and comun mandarin of Argentina and Uruguay and is reported to account for most of the mandarin production of those countries.  In the United States, it is grown as a collection item or dooryard ornamental.
      Presumably because of the fruit characteristics, processing of the Mediterranean mandarin has not been developed.  Two byproducts are made, however, principally, in Sicily: rind oil and oil of petit grain.  The rind oil is used in the preparation of perfumes and toilet waters and for the flavoring of confections and carbonated beverages.  Petit grain, which is distilled from the prunings and comes mainly from the leaves, has a strong and highly distinctive odor.
      The uniquely important, still unsolved problem with the Mediterranean mandarin is how to control its marked alternate-bearing tendency so as to regulate production and ensure fruit of good size.  Neither pruning nor fertilization, alone or in combination, have succeeded thus far.  Because of the highly delicate nature of the rind, all handling operations must be performed with special care to avoid fruit injury.  Despite such care, losses from decay are commonly excessive.
      According to Trabut (1902a, 1902b), the Clementine mandarin, now replacing the Mediterranean mandarin in parts of North Africa, is probably a natural hybrid of it and the Granito bitter orange, a view which has never received complete acceptance and seems highly doubtful.  However, this fruit is the pollen parent of three hybrid varieties currently of any interest in California and elsewhere—Encore, Kinnow, and Wilking—created by Frost (1935).  The seed parent of the hybrids is King mandarin.
      Two new varieties of Mediterranean mandarin have been reported in recent literature, the Tardivo di Ciaculli or Ciaculli Late of Italy (Zanini and Crescimanno, 1955) and an unnamed seedless clone in Spain (Gonzalez-Sicilia, 1963, p. 215).  A late-maturing variety would appear to afford little advantage, but a commercially seedless variety of good quality might well prove to be highly valuable.

Common Mandarins (Citrus reticulate Blanco)

      For reasons previously discussed, the writer has provisionally included in the common mandarins (Citrus reticulata Blanco)—one of the three species recognized by Swingle (chap. 3, this work)—thirteen of the fourteen species in Group III of Tanaka (1954).  These species are characterized by small flowers and leaves and medium to medium-large fruits.  As might be expected, this group is quite varied and exhibits a wide range in both tree and fruit characters.  In contrast with the three other species of mandarins presented in this treatment, some of the varieties characterized below are "tightskin" mandarins.  Although peelable, their rinds are much more tightly adherent than the "looseskin" mandarins and "puff" very little—if at all.  In addition, they usually have more solid axes.  Certain varieties also are included such as the Clementine, Ellendale, and Murcott, which have been or may be considered to be natural tangors.

     Major Common Mandarin Varieties.—The major varieties of common mandarins are described below.

Algerian
      See under Clementine.

Beauty (Beauty of Glen Retreat, Glen) (fig. 4-39)
      Fruit medium in size, oblate; base usually with well developed but small, more or less corrugated neck; apex somewhat depressed.  Rind thin, firm, but easily removed; surface smooth and glossy; color orange-red at maturity.  Segments 9 to 13, easily separated; axis medium and hollow.  Flesh orange-colored; tender; juicy; sprightly flavored.  Moderately seedy and cotyledons light-green.  Midseason in maturity.
      Tree vigorous, medium to large, upright-spreading, virtually thornless, with dense foliage consisting of medium-sized, broadly lanceolate leaves.  Strong tendency to alternate bearing with undesirably small and tart fruit in the "on" years.
      Beauty is said to have originated about 1888 as a seedling on the property of W. H. Parker, Glen Retreat, at Enoggera (a suburb of Brisbane), Queensland.  The parent variety is unknown but the similarities with Dancy are such C as to lead R. J. Benton, former government citrus specialist in New South Wales, to the conclusion that this variety is a seedling of the Dancy type, which is highly polyembryonic and reproduces remarkably true from seed.
      Beauty is highly popular in Queensland, where climatic conditions favor the production of large, superior quality fruit.  It is reported that overbearing in alternate years is successfully counteracted by a combination of heavy pruning and hand thinning.

Campeona (fig. 4-40)
      Fruit large (very large for mandarin), broadly oblate; base rounded and commonly short-necked with prominent radiating furrows or ridges; apex moderately depressed; smooth or with shallow radial furrows; commonly with small, embedded navel.  Rind medium-thick, comparatively soft, moderately adherent but readily peelable; surface roughly pebbled and somewhat bumpy with prominent, sunken oil glands; orange-colored at maturity.  Segments 10 to 13, moderately adherent; axis large and semi-solid to solid.  Flesh orange-colored; juicy; flavor rich and sprightly (somewhat acid).  Seedy to very seedy and cotyledons white.  Medium-late in maturity.
      Tree of medium vigor and size; branches numerous, slender, and thornless; foliage dense and composed of medium-sized, narrowly lanceolate, sharp-pointed leaves.
      Several competent observers have noted similarities between the fruits of Campeona and King in rind thickness and surface characteristics, color of the cotyledons, and lateness of maturity.  As a result, they have tentatively placed it in the King group (C. nobilis).  It is to be remarked, however, that tree descriptions of the King and Campeona do not correspond.  The Campeona has sometimes erroneously been called Bergamotta, a name that should be abandoned.
      In Entre Ríos Province of Argentina, where this variety has considerable and increasing importance, it is said that Campeona is of unknown Uruguayan origin and was introduced from Salta to the government citrus station at Concordia.  The quality, of the fruit is reported to be outstanding on Poncirus trifoliata rootstock.

Clementine (Algerian) (fig. 4-41)
      Fruit size variable, ranging from medium-small to medium; form likewise quite variable, with range from slightly oblate through globose to oblong and sometimes broadly pyriform from development of neck or collar; base usually rounded but sometimes collared or necked; apex depressed; occasionally with small navel.  Rind medium in thickness; moderately firm and adherent, but easily peelable and does not puff until well after maturity; surface smooth and glossy, but slightly pebbled because of prominent oil glands; color deep orange to reddish-orange, but not as red as Dancy.  Segments 8 to 12, slightly adherent; axis medium and open.  Flesh color deep orange; tender and melting; juicy; flavor sweet; subacid and aromatic.  Seeds very few to medium in number (depending on cross-pollination), monoembryonic, and cotyledons mostly green (some white).  Early inmaturity.  While the rind puffs somewhat after maturity, onsome rootstocks fruit holds on tree for several months with little loss in quality.
      Tree medium in vigor and size, spreading and round-topped; branchlets fine-stemmed, willowy, and nearly thornless; foliage dense.  Leaves highly variable in size, narrowly lanceolate in form, and somewhat resembling the Mediterranean or Willowleaf mandarin.  In most locations, regular and satisfactory bearing is assured only by the provision of cross-pollination.  Tree strongly cold-resistant.
      According to Trabut (1902a, 1902b, 1926) this highly important North African variety originated as an accidental hybrid in a planting of mandarin seedlings, presumably of the common or Mediterranean mandarin, made by Father Clement Rodier in the garden of the orphanage of the Péres du Saint-Esprit at Misserghin, a small village near Oran, Algeria.  It was one of several aberrant plants Trabut noted and was selected by him and named Clementine by the Horticultural Society of Algiers on his recommendation (Chapot, 1963a).  It was Trabut's conclusion that the seed parent was the Mediterranean mandarin and the pollen parent a willow-leafed ornamental variety of C. aurantium known as Granito.  Both Webber (1943, p. 558) and Tanaka (1954) have expressed doubt concerning the validity of this conclusion.  More recently, Chapot (1963a), the distinguished French authority in North Africa, has refuted it with convincing evidence.  It is his conclusion that Clementine is of Oriental origin, probably Chinese, and that it is indistinguishable from and probably identical to the Canton mandarin described by Trabut (1926), who also remarked on the similarities between the two.  If this Canton mandarin was authentic, these resemblances have apparently escaped the notice of Tanaka (1954), for he has given the species designation clementina to this mandarin.
      The Clementine variety was introduced into the United States in 1909 and brought to California from Florida in 1914 by H. S. Fawcett of the Citrus Research Center, Riverside.  Evidently another independent introduction was made, since the 1914-15 catalogue of the Fancher Creek Nurseries of Fresno, California, mentions a new early mandarin from Algeria which later proved to be indistinguishable from Clementine.
      At least two clones of Clementine are known to exist in North Africa—the common ordinary and the Montreal.  While the two are indistinguishable with respect to the tree, and virtually so for the fruit, the former exhibits self-incompatibility, and hence the fruit is seedless or nearly so in the absence of cross-pollination.  Evidently associated therewith is less regularity and certainty of production under unfavorable conditions of climate or orchard management.  The Monreal clone, which was found in 1940 in the orchard of Vincent Monreal at Perregaux, Oran, is self-compatible and without cross-pollination the fruit is regularly seedy.  The bloom is much less abundant and the seeds slightly smaller.  In this connection, it should be mentioned that seedy fruits average somewhat larger than seedless fruits and are also slightly sweeter.  In Morocco, selections from mother trees of outstanding bearing behavior and low seed content have not shown significant differences.  In both Morocco and Spain, seedless Monreal clones have been reported, butthus far they have not demonstrated superiority over the ordinary clone.  The Spanish clone, Clementino de Nules, is said to have originated as a budsport in Nules, Castellón Province.
      Chapot (1963b) has recently described a small-fruited mandarin which Trabut (1926, p. 4) either found or introduced and called the mandarinette.  It exhibits so many resemblances to Clementine, including seed monoembryony and early maturity, as to suggest very close relationship.  The principal differences reported relate to the odor of the leaf oil, the form of the seeds, and the color of the chalazal spot.
      Climatically, the distinctive features of the Clementine variety are its low total heat requirement for fruit maturity and the sensitivity of the seedless fruit to unfavorable conditions during the flowering and fruit-setting period.  In regions of high total beat, the Clementine matures very early—only slightly later than the satsuma mandarins.  Such regions also favor production of fruit of maximum size and best eating quality.  As a consequence, Clementine is without doubt the best early variety in the Mediterranean basin, particularly in North Africa, and is highly promising in other regions of similar climate.
      With reference to sensitivity of seedless fruits, however, the almost universal experience has been one of uncertain and irregular bearing behavior because of excessive shedding of young fruits during the fruit-setting period and a few weeks thereafter.  Moreover, it has been noted that shedding is inversely correlated with the seed content of the fruit.  Thus, it is well established that under conditions where the ordinary Clementine is notably capricious in bearing behavior the seedy Monreal is regularly productive.  Recently, it has been shown that the bearing behavior of the ordinary clone can be regularized by cross-pollination.  In descending order of effectiveness as pollinators in Morocco, Chapot (1963a, p. 14) lists sour or bitter orange, the Mediterranean, Dancy, and Wilking mandarins, the lemon, and the sweet oranges, including Valencia.  Soost (1963) recommends the use of Dancy and Wilking in the Coachella Valley of California.  There can scarcely be doubt, therefore, that the safest procedure is to provide suitable cross-pollinators or grow the Monreal clone, the fruits of which are commonly excessively seedy and hence less marketable.
      It should be pointed out, however, that the warm, equable, coastal regions of western Morocco enjoy climatic conditions that are normally favorable for fruit setting and permit the production of good crops of virtually seedless fruit.  Because of the high total heat, the fruit is exceptionally early in maturity and commands a premium in the export markets.  Moreover, even under conditions less favorable for fruit setting, it has been shown that regularity of bearing and increased production result from adequate nitrogenous fertilization and efficiency in irrigation.  Finally, it has been demonstrated that bearing can often be regularized and increased by means of a combination of girdling or ringing and light pruning—a tree management practice distinctive to the culture of this mandarin.  The procedure recommended consists of biennual double-girdling—at full bloom and the end of bloom, respectively—alternated with a light pruning to stimulate the development of new shoot growth.
      Application of these cultural practices has made it practicable for Moroccan growers to establish three export categories for this variety—seedless Clementines, Clementines (maximum of 10 seeds), and Monreal (more than 10 seeds).
      While accurate statistics are not available, there is reason to believe that the annual production of the Clementine in 1965 was in the neighborhood of 3.5 million 70-lb box equivalents.  Moreover, production seems likely to increase.  Morocco, where the Clementine is virtually the only mandarin grown, is the largest producer, followed by Algeria, Tunisia, and Spain.  In California and Arizona, plantings in 1964 were reported to be 1,403 acres.  No processing of the fruit has been reported to date.
      Because this variety is monoembryonic it is especially suitable as the seed parent for breeding purposes.  Clementine is the seed parent for a number of promising new mandarin-tangelo hybrids—Fairchild, Lee, Nova, Osceola, Page, and Robinson—recently released by the U.S. Department of Agriculture.  Clementine is also one of the parents of the Clement tangelo and the new Fortune and Fremont mandarins.

Clementino de Nules
      See under Clementine above.

Cravo (Laranja Cravo)
      Fruit medium to medium-large, slightly oblate or broadly obovate to subglobose, with moderately rough, rather loosely adherent rind of medium thickness and deep orange color.  Segments about 10, loosely adherent; axis large and hollow.  Flesh color deep orange; tender and melting; very juicy; flavor mild.  Seeds few to medium in number and cotyledons light green.  Very early maturity (in advance of Clementine).  Retains quality exceptionally well when stored on tree and puffs very little.
      Tree vigorous and large, upright in growth habit, but spreading under weight of crop; typical broadly lanceolate mandarin leaves.  Considerable tendency to alternate bearing with heavy crop of smaller fruit followed by a smaller crop of larger fruit.
      The Cravo is grown principally in São Paulo State of Brazil, where currently it constitutes about 10 per cent of the acreage.  The origin and history of this interesting variety are not known.  While it may be of local origin, the possibility exists that it was introduced from Portugal, since the descriptions of Cravo and Carvalhais correspond fairly well.

Cravo Tardia
      See under Ponkan.

Dancy (Dancy Tangerine) (fig. 4-42)
      Fruit medium in size, oblate to broadly obovoid or pyriform (from development of neck); base generally slightly but sometimes markedly necked; apex broadly depressed.  Rind thin, leathery, and tough; loose and easily removed, but not puffy until well past maturity; surface smooth and glossy, becoming bumpy with age; color deep orange-red to scarlet it maturity.  Segments about 12, easily separable; axis large and hollow.  Flesh deep orange-colored; tender and melting; moderately juicy: flavor rich and sprightly (acidity moderately high).  Seeds few to medium, small, highly polyembryonic, and cotyledons light green.  Midseason in maturity.  Loses quality rapidly and rind puffs badly if held on tree much after maturity, but stores moderately well.
      Tree vigorous and large (for the mandarins), upright-spreading in habit; nearly thornless; foliage moderately dense and of the mandarin type, but venation not so pronounced as in satsuma.  Productive but with some alternate-bearing tendency.  Tree moderately cold-resistant but not the fruit.
      Tanaka (1954) has placed Dancy in his species tangerina, winch he suggests originated in India and was early taken to southern China, where it is still extensively grown.  He considers it to be similar to if not identical with the Obenimikan of Japan, which was introduced from China several centuries ago.  He believes that it is closely related to the Ladu and Keonla mandarins of India, a view with which the writer is in accord.
      The history of Dancy's introduction into the United States (Florida), where it is currently the most important mandarin variety, is somewhat obscure.  According to Ziegler and Wolfe (1961) the original tree wasa seedling in the grove of G. L. Dancy at Orange Mills, Florida, which was planted in 1867.  The parent tree was known as the Moragne "tangierine" and was said to have been introduced from Tangiers (Morocco) and planted at Palatka by a Major Atway, whose place was acquired by N. H. Moragne in 1843.  The first mention of the Dancy variety is in the 1877 report of the Pomological Committee of the Florida Fruit Growers Association, in which it was said to be similar but slightly superior to the Moragne tangerine.  Although introduced to the industry as early as 1872, its commercial propagation was begun about 1890 by the Rolleston Nursery at San Mateo.  Within a few years, Dancy became the leading mandarin variety, a position it has maintained ever since.
      The high total heat and humidity of the Florida climate combine to provide an adaptation for this attractive and popular fruit that is unequalled elsewhere in the United States and is approached only in limited areas in other parts of the world.  This serves to explain why its commercial importance is restricted primarily to Florida.  Except for the hottest interior districts, where sunburn of exposed fruits is a hazard, fruit size is disappointingly small.  In arid or cooler climates and on most rootstocks, the flavor is too acid for the average palate.  Thus, in California and Arizona, fruit of acceptable size and quality is produced only in the low-elevation, desert regions.
      The importance of the Dancy variety is reflected by the fact that on several occasions in recent years the Florida crop has approximated 5.5 million 70-lb box equivalents.  Dancy production in California and Arizona in 1965 was about 250,000 boxes.  Although long since introduced into other parts of the citricultural world, for the reasons set forth above, this variety has failed to compete successfully with other, better adapted varieties.
      In recent years approximately 70 per cent of the Florida Dancy crop has been shipped fresh, the balance being processed for the juice—both single-strength canned and frozen concentrate.
      Of special interest is the fact that this variety has contributed to the parentage of the principal tangelos (Minneola, Orlando, Sampson, and Seminole), the Frua and Fortune mandarins, and the Dweet and Mency tangors.
      Frost Dancy, a nucellar selection that originated in 1916 from a cross made by H. B. Frost at the Citrus Research Center, Riverside, California, is currently the clone most propagated in the southwestern United States.  It was introduced commercially in 1952.  The Trimble and Weshart, which came from a Dancy tangerine-Parson Brown orange cross in the early breeding work of Webber and Swingle (1905), are now regarded as nucellar seedlings of Dancy rather than new varieties.  Neither seedling achieved commercial importance.

Ellendale (Ellendale Beauty) (fig. 4-43)
      Fruit medium large to large, oblate to subglobose; base rounded or short-necked; apex flat or slightly depressed; small navel frequent.  Rind medium-thin, smooth to faintly pebbled; relatively adherent though peelable at maturity; color orange-red.  Segments 10 to 12, readily separable; axis solid to semi-hollow.  Flesh bright orange-colored; very juicy; flavor rich and pleasantly subacid.  Moderately seedy with whitecotyledons, and strongly monoembryonic.  Late midseason in maturity.  Loses quality rapidly if left on tree much past maturity, especially on rough lemon rootstock, but stores well.
      Tree of medium vigor, spreading, round-topped, thornless, and productive.  Cold-resistant but subject to breakage because of weak crotches.
      This Australian variety is reported (Bowman, 1956) to have originated about 1878 as a seedling on the Ellendale property of E. A. Burgess at Burrum, Queensland, but did not come into prominence until much more recently.  Both Bowman (1956) and R. J. Benton, former government citrus specialist in New South Wales, consider it to be a natural tangor and the latter has called attention to similarities with the Temple variety as he saw it in Florida.  It is sometimes incorrectly called Fagan or Grant.
      In Queensland, Australia, where it is the principal variety, Ellendale attains maximum fruit size and excellent quality.  It is widely grown in New South Wales, however, and normally commands premium prices because of its large size, attractive color, and good keeping quality.  It is the latest maturing of the varieties currently grown commercially in Australia.
      A selection named Hearne is said to produce fruit of somewhat larger size and less tightly adherent rind.

Emperor (Emperor of Canton)
      Fruit large, oblate; base usually with short furrowed neck; apex flattened or slightly depressed.  Rind medium-thin, firm but fairly loosely adherent; surface moderately smooth; color yellowish-orange to pale orange.  Segments 9 to 10, readily separable; axis hollow.  Flesh color light orange; tender and juicy; flavor pleasant.  Seeds moderately numerous, long-pointed, and polyembryonic.  Early midseason in maturity.  Loses quality rapidly if stored on tree much past maturity.
      Tree moderately vigorous, medium-sized, upright, broad-spreading, virtually thornless, and productive.
      This very old variety in Australia is thought to have originated there as a seedling from fruit imported from the Orient.  R. J. Benton, former government citrus specialist in New South Wales, has stated that Emperor is very similar to if not identical with Oneco of Florida and Ponkan of China.  Of interest is the fact that this variety is still grown in seedling orchards in the Paterson River district of coastal New South Wales, where the trees markedly resemble those in the seedling districts of Coorg and Assam in India.  According to Bowman (1956), Emperor is probably the leading mandarin variety in Australia.  It is also grown to a limited extent in South Africa and northwest India.
      Late Emperor is said to have originated as a limb sport of Emperor and the South African Empress variety is reported to be a chance seedling of Emperor.

Encore
      Fruit medium insize, strongly oblate in form; rind thin and moderately adherent but easily peelable; surface texture smooth; color yellowish-orange.  Core hollow and segments about 11.  Flesh color deep orange; firm in texture, but tender and juicy; flavor rich.  Seeds numerous, monoembryonic, and cotyledons usually white.  Very late in maturity (fully as late as King) and holds especially well without loss of quality or much puffing of the rind.
      Tree moderately vigorous, upright-growing, and virtually thornless; many slender branches; density of foliage intermediate betweenthe parents.  Leaves resembling King, but with narrower blades and petiole wings.  Somewhat alternate bearing but productive.
      This promising, late-ripening variety originated from a cross of King and Willowleaf (Mediterranean) made by H. B. Frost at the University of California Citrus Research Center, Riverside.  Encore was selected and introduced in 1965 by Frost's colleagues, J. W. Cameron and R. K. Soost (Cameron, Soost, and Frost, 1965).

Fagan
      See under Ellendale.

Fairchild
      Fruit medium in size andmoderately oblate in form; rindmedium-thin, moderately adherent but easily peelable; surface texture smooth; color deep orange.  Flesh orange-colored; firm but tender and juicy; flavor rich and sweet.  Seeds numerous, small, and polyembryonic.  Early in maturity (about like Clementine but colors earlier).
      Tree vigorous, broad-spreading with dense foliage, nearly thornless, and productive.
      This exceptionally early, high quality, new variety, which was released in 1964, originated from a cross of Clementine mandarin X Orlando tangelo made by J. R. Furr of the U.S. Department of Agriculture at the U.S. Date and Citrus Station, Indio, California (Furr, 1964).  Fairchild is recommended for the desert areas of California and Arizona, where it is believed it may prove superior to Clementine.  Provision for cross-pollination is suggested until the facts in that connection have been determined.

Fewtrell (Fewtrell's Early)
      Fruit medium-small to medium, subglobose to broadly obovate; base usually rounded; apex flattened.  Rind medium in thickness; moderately adherent but easily peelable at maturity; texture and surface more orange-like than mandarin; color orange to reddish-orange at maturity.  Segments numerous (11-14); axis semi-hollow.  Flesh orange-colored; moderately juicy; flavor mild and not distinctive.  Seeds numerous.  Early in maturity (about like Imperial).
      Tree of medium vigor, spreading and round-topped, dense, symmetrical, and productive.  Strong tendency to alternate bearing with small fruit in "on-crop" seasons.
      Fewtrell is an old variety in New South Wales.  Its history and origin are unknown.  The characteristics of the fruit indicate that it may be a natural tangor and those of the tree suggest the possibility that Mediterranean or Willowleaf might have been the mandarin parent.
      This variety has been abandoned in the high rainfall districts of New South Wales.  It is reported as continuing to be popular in the interior Murray River districts of that state and the states of Victoria and South Australia, where it is said to alternate less strongly and early maturity coupled with ease of picking and packing have special importance.

Fortune
      Fruit medium to medium-large, moderately oblate; rind medium-thin, fairly tightly adherent but peelable; surface texture somewhat pebbled; color reddish-orange.  Flesh orange-colored; firm but tender and juicy; flavor rich and sprightly (subacid).  Seeds numerous, of medium size, and monoembryonic.  Late inmaturity and fruit holds well on tree with little loss in quality.
      Tree vigorous and spreading; dense canopy protects fruit against sunburn andcold; productive.
      This exceptionally late, high quality, attractive new variety originated from a Clementine X Dancy cross made by J. R. Furr (1964) of the U.S. Department of Agriculture at the U.S. Date and Citrus Station, Indio, California.  Fortune was released in 1964 and is recommended for the desert regions of California and Arizona.  Provision for cross-pollination is suggested until the facts in that connection are known.

Fremont
      Fruit medium in size, oblate in form; rind medium-thick and of moderate adherence (easily peelable); surface smooth; color bright reddish-orange.  Flesh color deep orange; tender and juicy; flavor rich and sprightly.  Seeds moderately numerous, small to medium, and about half of them monoembryonic.  Early ripening (between Clementine and Dancy), but fruit retains quality exceptionally well past maturity.
      Tree moderately vigorous, upright-growing, nearly thornless, precocious, and productive, but does not shade fruit sufficiently well to prevent some sunburn.
      Fremont is an attractive, high quality, early-ripening variety that originated from a Clementine X Ponkan cross made by P. C. Reece of the U.S. Department of Agriculture at the U.S. Horticultural Field Station, Orlando, Florida.  It was first fruited at Brawley, California, selected by J. R. Furr (1964) of the U.S. Date and Citrus Station, Indio, California, and released in 1964.  Fremont is recommended for the desert areas of California and Arizona.

Frost Dancy
      See under Dancy.

Glen
      See under Beauty.

Grant
      See under Ellendale.

Hearne
      See under Ellendale.

Imperial (Early Imperial)
      Fruit medium-small to medium, oblate to broadly obovate; short basal neck or low collar; apex depressed.  Rind very thin, leathery, smooth and glossy, with slight adherence but no puffing until mature; color yellowish to pale orange at maturity.  Segments 9 to 11, easily separable; axis medium and hollow.  Flavor pleasantly subacid with attractive aroma.  Comparatively few seeds.  Very early in maturity (about like Wase satsuma).  Loses quality if left on tree after maturity.
      Tree vigorous, medium in size, upright, virtually thornless; leaves long, slender, and taper-pointed.  Some tendency to alternate bearing.
      Imperial originated about 1890 at Emu Plains, some thirty miles west of Sydney, New South Wales, and is believed to be a chance hybrid of Mediterranean or Willowleaf, to which it bears considerable resemblance, and some other mandarin—possibly Emperor.  Because of its early maturity, attractive appearance, and pleasant flavor, it commands a premium in the markets

Kara
      Fruit medium-large, moderately to slightly oblate; base commonly slightly necked and furrowed; apex flattened or depressed with visible areolar area.  Rind medium-thick, soft in texture, moderately adherent but peels fairly well; surface slightly rough and bumpy; color deep orange at maturity.  Segments 10 to 12, separable without difficulty; axis medium and semi-hollow.  Flesh color deep orange; tender and juicy; flavor rich, sprightly, and distinctive (tart until very mature).  Seeds polyembryonic, numerous and cotyledons pale greenish-yellow.  Very late in season of maturity (slightly ahead of King).  Retains quality if left on tree but puffs somewhat.
      Tree moderately vigorous, spreading and round-topped; similar to satsuma but larger and more vigorous; thornless, with rather stout, spreading and drooping branches; leaves dark green and satsuma-like.  Hardy to cold and productive.  Slight tendency to alternate bearing.
      This very late ripening and richly flavored variety is an Owari satsuma-King mandarin hybrid created in 1915 by H. B. Frost (1935) of the University of California Citrus Research Center, Riverside, and named and introduced in 1935.  Though outstanding in flavor, Kara has not achieved commercial importance, presumably because of the competition provided by oranges at its season of maturity, and its seediness.

Kinnow (fig. 4-44)
      Fruit medium in size, moderately to slightly oblate; both base and apex flattened or slightly depressed.  Rind thin, rather adherent for a mandarin but peelable, tough and leathery; surface very smooth and glossy, sometimes faintly pitted; color yellowish-orange at maturity.  Segments 9 to 10, firm, separating fairly easily; axis solid to semi-hollow.  Flesh color deep yellowish-orange; very juicy; flavor rich, aromatic, and distinctive.  Seeds numerous, polyembryonic, and cotyledons pale greenish-yellow.  Midseason in maturity (about like Dancy).  Fruit holds well on tree with little puffing.
      Tree vigorous and large, tall and columnar, with numerous long, slender, ascending, and virtually thornless branchlets; dense foliage consists of medium-large, broadly lanceolate leaves.  Rather strong tendency to alternate bearing with large crop of smaller fruits followed by very small crop of larger fruits.  Cold-resistant.
      This high-quality variety is a sister to Wilking, both resulting from a King-Willowleaf (Mediterranean) mandarin cross made in 1915 by H. B. Frost (1935) of the University of California Citrus Research Center, Riverside, California, and named and released in 1935.  Kinnow has been distributed widely and is currently grown commercially to some extent in California, Arizona, West Pakistan, and India (Punjab).  The total plantings in California (mainly the Coachella Valley) and Arizona in 1964 were estimated at 900 acres.

Kosho Tankan
      See under Tankan.

Laranja Cravo
      See under Cravo.

Lee
      Fruit medium insize, slightly oblate to subglobose; basal area slightly raised and furrowed; apex evenly rounded or slightly flattened.  Rind thin, leathery, moderately adherent but readily peelable; surface smooth and glossy: color deep yellowish-orange at maturity.  Segments 9 to 10, readily separable; axis large and hollow.  Flesh color orange; tender and melting; juice abundant; flavor rich and sweet.  Seeds numerousand cotyledons light green.  Medium-early inmaturity.
      Tree not distinctive, nearly thornless; dense foliage comprised of medium-sized, lanceolate leaves.
      This new early hybrid variety is one of three (Lee, Osceola, Robinson) resulting from a cross of Clementine mandarin X Orlando tangelo made by Gardner and Bellows of the U.S. Department of Agriculture in Florida in 1942 and released in 1959 (Reece and Gardner, 1959).  Lee is currently under commercial trial in Florida.  Since the parent varieties respond to cross-pollination, it seems likely that the daughter varieties will respond similarly.

Monreal
      See under Clementine.

Murcott (Murcott Honey, Smith) (fig. 4-45)
      Fruit medium in size, firm, oblate to subglobose; shallowly ribbed to conform with segments; both base and apex flattened or slightly depressed.  Rind thin, rather tightly adherent and not readily peelable; surface smooth to slightly pebbled; color yellowish-orange at maturity.  Segments 11 to 12, moderately adherent; axis medium-large and semi-hollow.  Flesh orange-colored; tender, very juicy; flavor very rich and sprightly.  Seeds small, few to numerous, and cotyledons white.  Medium-late in maturity.  Holds only moderately well on tree with some granulation but does not puff.  Ships exceptionally well.
      Tree medium in vigor and size, upright-growing with long, willowy branches; leaves medium-small, lanceolate, and sharp-pointed.  Fruit mainly borne terminally and hence exposed to wind, frost, and sunburn injury.  Productive but with tendency to alternate bearing and one of the most sensitive mandarins to cold.
      To avoid confusion with the hybrid Honey mandarin variety of California origin, the name Honey should not be used for this variety even as an appendage.  Likewise, the name Smith should be dropped since Murcott clearly has priority.
      The origin of Murcott is unknown and its history obscure.  The oldest known budded tree, from which the present commercial acreage largely if not entirely traces, still remains on the place formerly owned by a nurseryman, Charles Murcott Smith, in Bayview, Clearwater, Florida, and is thought to have been budded about 1922 (Ziegler and Wolfe, 1961).  It is believed that the budwood was obtained from a neighbor, R. D. Hoyt of Safety Harbor, who was a cooperator in the citrus breeding program of the U.S. Department of Agriculture, which maintained a nursery of citrus hybrids at Little River, Miami, until about 1916.  Evidently the parent tree was one of the hybrids which Mr. Hoyt received from the Department of Agriculture nursery at Miami sometime prior to 1916.  Unfortunately, records are not available concerning this transaction or the labels for the trees provided.  Under the name Honey Murcott, small-scale commercial propagation was undertaken by the Indian Rocks Nursery in 1928.  The first commercial planting, which brought this variety to prominence and is largely responsible for its present popularity, seems to have been that of J. Ward Smith (no relation to C. Murcott Smith), near Brooksville in 1944, who first marketed the fruit under the name Smith tangerine, apparently unaware that it had already been named.
      It is the consensus of Florida horticulturists that this variety is a tangor of unknown origin resulting from the breeding program of the U.S. Department of Agriculture.
      During the past decade, Murcott has been planted rather extensively, in Florida.  The 1961 plantings, mostly nonbearing, were reported at 5,400 acres and the 1961-62 crop at approximately 175,000 boxes (70-lb equivalents).  Because of its rich flavor and deep orange-colored flesh and juice, Murcott is a favorite with gift fruit packers.

Nagpur
      See under Ponkan.

Nova
      Fruit much like Orlando in size and form, medium-large, oblate to subglobose and without neck; base slightly rounded; apex nearly flat.  Rind thin, leathery, moderately adherent but easily peelable; surface slightly pebbled; color deep yellowish-orange at maturity (deeper than Orlando).  Segments about 11, easily separable; central axis medium in size and open.  Flesh color deep orange; juicy; flavor pleasant.  Seeds numerous in mixed plantings, polyembryonic, and with light green cotyledons.  Colors and matures very early (considerably ahead of Orlando).
      This very early ripening variety is a sister to the Lee, Osceola, and Robinson mandarins, all four resulting from a Clementine mandarin-Orlando tangelo cross made in 1942 by Gardner and Bellows of the U.S. Department of Agriculture at Orlando, Florida, and described and released in 1964 (Reece, Hearn, and Gardner, 1964).  Since its parents are strongly self-incompatible and more fruitful if cross-pollinated, it seems likely that Nova will exhibit the same characteristics.

Oneco
      See under Ponkan.

Ortanique (fig. 4-46)
      Fruit large (very large for mandarin), very broadly obovoid to slightly oblate to almost subglobose; base evenly rounded or tapering to low, shallowly furrowed neck or collar; apex flattened or with shallow depression and sometimes with small protruding navel; areole evident though not prominent.  Rind thin, leathery, rather tightly adherent but peelable; surface smooth but finely pitted, glossy; color bright yellowish-orangeat maturity.  Segments 10 to 12; axis solid to semi-open.  Flesh orange-colored; juicy; flavor rich and distinctive.  Seeds average about 10, plump, with white cotyledons, and polyembryonic.  Late midseason in maturity and holds well on tree.
      Tree moderately vigorous, medium-large, spreading and drooping, almost thornless, with slender branchlets; dense foliage consists of medium-sized leaves with narrowly winged petioles.
      The origin of this attractive and promising variety is unknown, but Ortanique is reported (Anonymous, 1963) to be an old chance seedling that came to the attention of C. P. Jackson of Chellaston, Mandeville, Jamaica, in 1920.  He is said to have grown 130 seedlings from it, of which about 40 per cent resembled the parent fruits, and to have selected those which he considered best.
      Because of the presence of wild orange and so-called tangerine trees in the vicinity of the original tree and the distinctive features of the fruit, it was considered to be a natural tangor and was given the name Ortanique by H. H. Cousins, a former Director of Agriculture.  The name was a synthesis coined from or(ange), tan(gerine), and (un)ique.  The present clone probably represents a nucellar seedling of the parent tree.  It is worth noting that two other high quality, mandarin-like varieties—Temple and Ugli—are believed to have originated as wild chance seedlings in Jamaica.
      Although Ortanique early gained popularity in the local markets, it was not planted much until comparatively recently when small shipments to Canada and Great Britain received favorable market reactions and brought high prices.  Acreage was said to be approximately 2,000 in 1964 when about 1,200 acres were six years old or less.  The Jamaica Citrus Growers' Association reported that its handlings increased from 22,246 field boxes in 1960-61 to 73,616 boxes in 1962-63 and were expected to reach 250,000 boxes by 1967.

Osceola
      Fruit medium in size, medium-oblate in form; base flattened and sometimes slightly corrugated; apex flattened or slightly depressed.  Rind thin, leathery, moderately adherent but easily peelable; surface smooth and glossy; color deep orange to almost coral-red at maturity.  Segments 10 to 11, easily separable; axis large and hollow.  Flesh color deep orange; juicy; flavor rich and distinctive.  Seeds numerous and cotyledons very pale green.  Medium-early in maturity.
      Tree not distinctive, virtually thornless, more upright than Clementine; dense foliage composed of medium-sized lanceolate leaves.
      This exceptionally high-colored, early variety is a sister to Lee and Robinson, all three resulting from a Clementine mandarin-Orlando tangelo cross made by Gardner and Bellows of the U.S. Department of Agriculture in Florida in 1942 and released in 1959 (Reece and Gardner, 1959).  Osceola is currently under commercial trial in Florida.  It seems likely that it will respond to cross-pollination since both parent varieties are strongly self -incompatible and more fruitful when seedy.

Page
      Fruit of medium size, broadly oblate to subglobose; apex evenly rounded.  Rind medium-thin, leathery, moderately adherent but easily peelable, surface smooth to moderately pebbled; color reddish-orange at maturity.  Segments about 10 and central axis solid to slightly open.  Flesh color deep orange; tender and juicy; flavor rich and sweet.  Seeds moderately numerous and cotyledons pale yellow to almost white.  Early in maturity.
      Tree moderately vigorous; branches upright, spreading under the weight of fruit, nearly thornless; productive.
      This early ripening, high quality variety, the fruit of which has considerable resemblance to a sweet orange, originated from a Minneola tangelo X Clementine mandarin cross made by Gardner and Bellows of the U.S. Department of Agriculture in 1942.  Page was described and released in 1963 by P. C. Reece and F. E. Gardner at the U.S. Horticultural Field Station, Orlando, Florida.  It is recommended for Florida conditions and the fruit may be undesirably small in arid climates.  Cross-pollination should be provided until the facts in that connection have been determined.
      While officially released as an orange, technically speaking this variety should probably be referred to the tangelo hybrid group, since its parentage is three-fourths mandarin and one-fourth grapefruit.

Ponkan (Nagpur, Warnurco) (fig. 4-47)
      Fruit large (for a mandarin), globose to moderatelyoblate; base commonly with strong furrowed but relatively short neck or lowcollar; apex usually deeply depressed and with radiating furrows; sometimes with naval.  Rind medium-thick, fairly loosely adherent; surface relatively smooth but pebbled, with prominent, sunken oil glands; orange-colored at maturity.  Segments about 10, easily separable; axis large and hollow.  Flesh color orange; tender and melting, juicy; flavor mild and pleasant, and aromatic.  Seeds few, small, plump, and polyembryonic; cotyledons light green.  Early midseason in maturity.  Loses quality and rind puffs if not picked when ripe.
      Tree commonly vigorous and distinctive in appearance because of pronounced upright growth habit.  Productive but with strong alternate-bearing tendency.  Reported to be less cold-resistant than most mandarins.
      This is the famous and highly reputed ponkan of South China and Formosa, the Batangas mandarin of the Philippines, and the Nagpur suntara or santra (various other spellings) of India.  Other names that occur in the literature and should best be dropped include Swatow orange and Chinese Honey orange.
      Tanaka (1927) is of the opinion that this mandarin originated in India and because of its excellence spread widely throughout the Orient at an early date.  This view finds support in the fact that for centuries it has been cultivated in the form of seedling groves in widely separated parts of India—notably in the Coorg district in the south and Assam and neighboring Nepal and Sikkim in the northeastern portion of that country.  As previously noted, there is reason for believing that this fruit reached Europe as early as 1805.  The first known introduction into the United States, however, is referred to 1892 or 1893 when an American medical missionary in China sent fruits to J. C. Barrington of McMeekin, Florida, from which seedlings were grown.  One of these was later identified as Ponkan (Tanaka, 1929a).  Prior to this identification, however, the Wartmann Nursery Company at Ocala had propagated this fruit on a limited scale under the name Warnurco tangerine.  More recent introductions have been made by the U.S. Department of Agriculture.
      Because of its highly distinctive characteristics and his conclusion that the Batangas mandarin was the fruit described by Blanco under the species name reticulata, Tanaka (1954) restricted this species to the Ponkan group, a view which in the judgment of the writer has considerable merit, although it has not been generally accepted.  Several forms or clones are recognized of which that characterized above and known in India as Nagpur suntara is clearly superior.  Almost certainly the highly important seedling varieties known variously as Coorg, Assam, Khasi, Butwal, and Sikkim in India are nucellar clonal budlines of the Nagpur suntara.  In this connection, it may be of interest to note that the variety Oneco, which originated in Florida from seed received by P. W. Reasoner in 1888 from northwestern India, has been identified as a form of ponkan (Tanaka, 1929a).  Oneco differs, however, in that the fruit is rougher and seedier, ripens somewhat later, and retains its quality on the tree much better, although the rind puffs rather badly.  Oneco has never achieved commercial importance and is grown primarily as a home and gift-box fruit.  Oneco appears to be the Cravo Tardia of Brazil.
      The Nagpur suntara is the citrus fruit of greatest commercial importance in India.  While accurate statistics are not available, it is believed that the total plantings of this variety and its seedling derivatives are in the neighborhood of 100,000 acres.  The modern commercial industry based on the use of budded trees centers in the Nagpur region of central India, where a small but growing processing industry has developed.  Elsewhere this fruit has importance in Ceylon, Indonesia, Malaysia, the Philippines, South China, Taiwan, and the southern part of Kyushu Island, Japan.  It is of limited importance in Brazil and very minor importance in Florida.
      Climatically, the ponkan is one of the most tropical mandarins.  Under tropical conditions the fruit attains maximum size and quality and finds little competition from other mandarins.  In the hot arid subtropics, however, it has generally proven disappointing and other varieties are better adapted and more popular.
      Much the most unusual and distinctive cultural practice is that followed in central India, where the growers select and accentuate one of the three periods of bloom characteristic of the mandarin tree there to control the time of maturity and increase the resultant crop.  This is accomplished by what is commonly referred to as the "resting treatment" (Gandhi, 1956, pp. 32-35).  In reality, it is a combination of treatments that place the trees under severe moisture stress from which they are released either by irrigation or the advent of the summer monsoon rains.  The practice is similar to that employed by Sicilian lemon growers to accentuate the early fall bloom and increase the summer or verdelli crops.  The differences in the characteristics of the fruit from the spring and fall blooms are remarkable.
      Another distinctive practice has already been mentioned, namely, the exclusive use of unbudded seedling trees in the important Coorg and Assam regions.  The resulting orchards are remarkably uniform, and the trees extremely tall and slender.

Robinson
      Fruit medium-large, oblate (more so than Osceola): base evenly rounded or slightly necked; apex broadly depressed.  Rind thin, tough and leathery, moderately adherent but easily peelable: surface smooth and glossy; color deep yellowish-orange at maturity.  Segments numerous (12-14), readily separable; axis large and hollow.  Flesh color deep orange; juicy; flavor rich and sweet.  Seeds moderately numerous and cotyledons light green.  Early in maturity (about the same as Lee and Osceola but colors earlier).
      Tree upright-spreading, nearly thornless; dense foliage consists of large broadly lanceolate, taper-pointed leaves, commonly notched at the tip and crenate-margined on the upper half.  Appears to be a regular bearer.
      This very early maturing, rather large-fruited variety is a sister to Lee and Osceola, all three resulting from a Clementine mandarin-Orlando tangelo cross made by Gardner and Bellows of the U.S. Department of Agriculture in Florida in 1942 and released in 1959 (Reece and Gardner, 1959).  Robinson is currently under commercial trial in Florida.  Since its parents are both self-incompatible and more fruitful if cross-pollinated, it seems likely that Robinson will exhibit the same characteristics.

Smith
      See under Murcott.

Tankan
      Fruit medium-large to large, subglobose to broadly pyriform (from development of neck); base rounded or with more or less prominent and furrowed neck; apex slightly rounded or flattened.  Rind medium-thick (for mandarin), moderately adherent but readily peelable; surface pebbled and commonly somewhat wrinkled; deep orange-colored at maturity.  Segments about 10, readily separable: axis semi-hollow.  Flesh deep orange; tender, very juicy; flavor rich and sweet.  Seeds few to many.  Medium-late in maturity.  Retains quality when held on tree and ships and stores well.
      Tree of medium vigor and size, upright, virtually thornless; leaves medium-large, broadly lanceolate, and taper-pointed, with midribs strongly prominent above and petioles margined to narrowly winged.  Productive.
      According to Tanaka (1929b), the Tankan is a very old variety that originated in southeastern China and early spread to Formosa and Japan, where its culture is confined to the hotter portions of Kagoshima Prefecture.  Tanaka considers it to be one of the finest citrus fruits of the Orient.  While the tree characters are almost entirely mandarin, the fruit exhibits certain features which suggest the possibility that it is a natural tangor.  It is classified by Tanaka (1954) as C. tankan Hayata.
      Kosho Tankan is a Formosan derivative that is characterized by fruit of larger size, superior quality, and later maturity.

Trimble
      See under Dancy.

Warnurco
      See under Ponkan.

Weshart
      See under Dancy.

Wilking
      Fruit small to medium in size, slightly oblate; base flattened and somewhat furrowed; apex flattened or moderately depressed.  Rind medium-thin, somewhat brittle, somewhat adherent but readily peelable; surface slightly pebbled, glossy.; orange-colored at maturity.  Segments 9 to 12, firm but separating easily; axis semi-hollow.  Flesh color deep orange; very juicy; flavor rich, sprightly, aromatic, and distinctive.  Seeds moderately numerous, monoembryonic, and cotyledons greenish-yellow to yellow-tinged.  Midseason in maturity (about like Kinnow).  Retains quality and stores well on tree but with some puffing.
      Tree moderately vigorous, medium in size, round-topped, nearly thornless; leaves long, broadly lanceolate, and taper-pointed.  Strong tendency to alternate bearing with small fruits in the on-crop seasons and little or no fruits in the off-crop years.  Cold-resistant.
      A sister to Kinnow, both resulting from a cross of King X Willowleaf (Mediterranean) made in 1915 by H. B. Frost (1935) of the University of California Citrus Research Center, Riverside, this richly flavored variety has been widely distributed, but with minor exceptions has not achieved commercial importance.  Wilking is reported to have done well commercially, however, in the Souss Valley of Morocco and is considered promising in Brazil.

     Minor Common Mandarin Varieties.—The common mandarins discussed in the subsection below are of lesser commercial importance, local interest, or still have not proven themselves.

Burgess (Solid Scarlet)
      This Australian variety produces a late-ripening, relatively tight-skinned fruit much like Ellendale but somewhat deeper in color.  It originated in 1908 as a seedling of Ellendale grown by E. A. Burgess at Burrum, Queensland.  Burgess is not related to Scarlet and is declining in importance.

Capurro
      Fruit medium-large, strongly oblate; orange-colored; seedy.  Relatively loose rind of medium thickness.  Numerous slightly adherent segments.  Abundant juice; flavor rich and somewhat tart.  Cotyledons green.  Early maturity.
      Tree vigorous and large with numerous fine, nearly thornless branchlets; moderately dense foliage composed of long, lanceolate, taper-pointed leaves.
      This Argentinian variety is reported to have originated fairly recently as a chance seedling in the Capurro orchard in Colonia Yerua, near Concordia, Entre Ríos Province.  Capurro is of minor but growing importance in Argentina.

Carvalhais (Tangera) (fig. 4-48)
      Fruit medium to medium-large, oblate to almost globose; basal area somewhat furrowed and commonly short necked; apex rather deeply depressed, usually with prominent areolar area and ring.  Rind medium-thick, tough, rather strongly adherent; orange when fully colored.  Flesh juicy and pleasantly subacid early in season, but loses quality thereafter.  Seeds numerous and highly polyembryonic.  Maturity very early (fully as early as Clementine), occurring much in advance of rind color development.  Fruit holds well on tree with little puffing.
      Tree vigorous, upright in habit; leaves distinctive, long, and sharp-pointed, somewhat resembling the Clementine.
      Carvalhais is of unknown but almost certainly local Portuguese origin.  It is thought to be a natural hybrid of which one parent is the Mediterranean mandarin, known locally as Setubalense.  Carvalhais has commercial importance in Portugal and is exported to a small extent to nearby countries—particularly Morocco and Algeria.

Empress
      Fruit similar to Emperor but averages smaller, is somewhat seedier, and seeds are said to be more highly polyembryonic.  Also stores better on the tree, which is more vigorous and upright in growth.
      Empress originated as a chance South African seedling, believed to be of Emperor, in the Watkinson Nurseries at Nelspruit, eastern Transvaal.  It was selected by R. H. Marloth of the Citrus and Subtropical Fruit Research Institute at Nelspruit about 1932.  Although the fruit is popular in the local markets, this variety is of primary interest in South Africa as a rootstock.

Frua
      Fruit medium-sized, slightly necked, somewhat pebbled.  Reddish-orange with few seeds and mild, sweet flavor.  Rind puffs rather badly.  Early midseason in maturity (earlier than Dancy, which it somewhat resembles).  Tree lacks vigor.
      Frua is a hybrid of the King mandarin with the Dancy tangerine developed from a cross made by H. B. Frost of the University of California Citrus Research Center, Riverside.  It was selected in 1925 and released in 1950.

Hansen
      Hansen is a late variety that follows Ellendale, which is currently under trial in South Australia.  It may be a tangor.

Hickson
      This midseason Australian variety originated in Queensland, where it is currently under trial.  Hickson may be a tangor.

Honey
      Fruit small-sized, oblate; rind faintly pebbled; seeds numerous.  Light yellowish-orange; flavor rich and sweet.  Matures early.  Tree vigorous and tends strongly to alternate bearing.
      Honey is a hybrid of the King mandarin with the Willowleaf (Mediterranean) mandarin made by H. B. Frost of the University of California Citrus Research Center, Riverside.  This hybrid is a sister of Encore, Kinnow, and Wilking.  It was described in 1943 but never released officially.

Kaula (Keonla)
      Kaula is a highly colored, strongly oblate, short-necked, and apically depressed fruit of medium size and good flavor.
      Kuala is of Indian origin and local importance only.  Tanaka has classified this fruit as C. crenatifolia Lush.

Keonla
      See under Kaula above.

Ladoo
      See under Ladu below.

Ladu (Ladoo)
      This Indian variety produces an attractive, reddish-orange, nearly seedless, slightly necked, oblate fruit of medium size and good flavor.  The tree is vigorous, dense, round-topped, and productive.
      Ladu is of unknown but presumably Indian origin.  Gandhi (1956) reports that it has commercial importance in Uttar Pradesh and parts of the Deccan.  Tanaka (1954) classified this fruit as C. paratangerina Hort. ex Tan.

Late Emperor
      This Australian variety is indistinguishable from Emperor, but the fruit matures about a month later.  It is said to be a limb sport of the Emperor variety.

Malvasio
      Fruit medium in size, oblate to subglobose; neck short and furrowed; often with small navel; moderately seedy.  Rind orange-colored, thin, relatively adherent but peelable; about 10 moderately adherent segments; semi-hollow axis.  Good juice content and pleasant subacid flavor.  Cotyledons light green.  Maturity very late.  Holds well on tree and stores well.
      Tree vigorous, large, and broad-spreading with some strong and distinctive horizontal branches.  Leaves of medium size, lanceolate with apex blunt and notched.
      This Argentine variety was found in an orchard (details not available) near Concordia, Entre Ríos Province, and is believed to have originated as a chance seedling.

Mandalina
      This Lebanese variety closely resembles Dancy and produces an attractive, reddish-orange, seedy, loose-skin fruit of midseason maturity and mediocre quality.  The rind puffs badly.  Mandalina is of little importance and apparently an old variety of unknown origin.

Muscio
      This Australian variety produces a very late-ripening fruit of good size and quality.  It is strongly alternate bearing, however.

Naartje
      Fruit medium to medium-large, firm, and moderately seedy.  Strong rind adherence (though peelable).  Color orange to orange-red and flavor rich.  Midseason maturity.  Good shipping quality.
      Tree of medium vigor and size, spreading, round-topped, and virtually thornless; fairly dense foliage consisting of large, dark-green leaves.
      Of unknown Oriental origin, Dutch traders early introduced a distinctive type of mandarin to South Africa, which was given the name naartje, presumably by the Boer settlers.
      Until comparatively recently propagation was by means of seedlings, which exhibit remarkably little variation, apparently because the seeds are highly polyembryonic.  The principal named clonal varieties currently are Natal Tightskin and Redskin, the latter being characterized by somewhat deeper rind color.  It is said to closely resemble the Australian variety Beauty.

Natal Tightskin
      See under Naartje above.

Parker (Parker Special)
      The fruit of this midseason Australian variety is large, reddish-orange, and attractive, but the flesh is poorly flavored.  The tree is of good bearing behavior.

Pixie
      Fruit small to medium-small, subglobose to round; commonly with broad, short neck and collar.  Rind medium-thin, easily separable; grained to pebbled surface texture; color yellowish-orange.  Flesh medium-orange; moderately juicy; flavor pleasant and mild.  Virtually seedless (occasionally 1 seed).  Holds well on tree with little rind-puffing, but some juice loss.  Matures late.
      Tree vigorous, erect to somewhat spreading; stout, ascending branches and large, King-like leaves.  Tendency to alternate bearing.  Considerable proportion of inside fruits not subject to sunburn.
      Pixie is a second generation seedling (hybrid or self) from open pollination of a cross of King and Dancy (named Kincy).  This variety was made in 1927 by H. B. Frost of the University of California Citrus Research Center, Riverside, and was selected and introduced in 1965 by his colleagues J. W. Cameron and R. K. Soost.  Because of its seedlessness and lateness of maturity, Pixie may have promise, especially as a home orchard variety (Cameron, Soost, and Frost, 1965).

Redskin
      See under Naartje.

Sanguigno (Sanguine in North Africa)
      This Italian variety of unknown origin produces an attractive medium-sized, seedy, deep reddish-orange fruit of midseason maturity and indifferent quality.  The fruit puffs badly and keeps poorly.  Both tree and fruit markedly resemble the Scarlet variety of Australia.
      The name is a misnomer, for this variety is not a true blood mandarin.  Indeed, the writer does not know of any pigmented true mandarins.

Scarlet
      Scarlet is an old Australian variety no longer grown commercially.  It produces a medium-sized, seedy, reddish-orange fruit of early midseason maturity that puffs excessively, and keeps poorly.  The tree is productive.

Solid Scarlet
      See under Burgess.

Som-Chuk (Somjook, Necked Orange)
      Fruit large, round to obovate, with prominent neck.  Rind medium-thick and readily peelable.  Easily separable segments and open center.  Flesh juicy and of rich subacid flavor.  Tree vigorous, upright, and thorny.
      This highly reputed mandarin, the so-called necked orange, is possibly a natural tangor.  Som-Chuk is an old variety of unknown origin that is grown mainly in the southern peninsular area of Thailand, where it is propagated by seed only.  The descriptions and illustrations available (Wahlberg, 1958, and personal communication) suggest close resemblance to the Ponkan.¹⁶

Somjook
      See under Som-Chuk, above.

Stemp
      This midseason Australian variety originated in Queensland, where it is currently under trial.  Stemp is much like Hickson and may be a tangor.

Wallent
      Fruit medium-small, reddish-orange, and of attractive appearance.  Rind thin and relatively tight-skinned.  Distinctive, sprightly flavor.  Colors early, but remains too acid for many palates until late midseason.  Tree strongly alternate in bearing behavior.
      Wallent originated as a chance seedling in a home garden in Adelaide, South Australia, and was introduced by a Mr. Wallent of Wambaral, Gosford, New South Wales.  It was popular locally for some time but has been little planted in recent years.

Small-fruited Mandarins

      Groups IV and V of the Tanaka (1954) classification contain a total of sixteen species and are characterized by small flowers, fruits, and leaves.  The leaves are narrow in Group IV and broad in Group V.  Of these species the writer has seen eleven but possesses some degree of competence for only three.  Some of these Citrus species may be subject to question, but those with which the writer is acquainted—indica, tachibana, and reshni—appear to constitute valid species.  Currently seven species are of horticultural importance or promise:
      1. Citrus amblycarpa Ochse—This is the djerook leemo of Java.  The tree is highly distinctive.  The fruit is very small, tight-skinned, yellow, and very acid, with polyembryonic seeds and green cotyledons.  The species is experimentally promising as a rootstock in California.
      2. Citrus depressa Hayata (formerly C. pectinifera Tan.)—This species is the shiikuwashâ of Okinawa and Taiwan and shekwasha or sequasse in collections in the United States.  The tree is vigorous, round-topped, and finely stemmed.  The fruit is very small, orange-colored, oblate, and highly depressed at both ends, with very thin, loose, and aromatic rind.  The flesh is soft, gelatinous, and acid, but ultimately attains a rich flavor.  The seeds are polyembryonic with green cotyledons.  The tree makes an attractive ornamental.
      3.Citrus kinokuni Hort. ex Tan.—This species is the kishû mikan of Japan.  The fruit is small, somewhat oblate, depressed at both ends, orange-colored, and glossy.  The thin, comparatively tight rind is easily peelable and fragrantly aromatic.  The flesh is firm, meaty, and pleasantly sweet in flavor.  Seeds are few, polyembryonic, and have pale green cotyledons.  Fruit maturity occurs in early midseason.
      The kinokuni is said to be a very old species of Chinese origin and one of the earliest introduced into Japan, where it is still popular because of its pleasant flavor and rich fragrances Tanaka (1954, p. 136) states that at least four varieties are known, the largest of which is Hirakishu (fig. 4-49).  Mukakukishu is a completely seedless variety.
      4. Citrus lycopersicaeformis Hort. ex Tan.—This species is the kokni or kodakithuli of southern India.  The fruit is very small, moderately oblate to obconical, deep orange, and has a thin, moderately loose rind.  The flesh is somewhat coarse-grained, dry, and acid but becomes edible at full maturity.  Seeds are polyembryonic with green cotyledons.
      This species is considered to be native to India and can be found in markets there.  Tanaka (1954, p. 140) reports that the heennaran of Ceylon is identical.
      5. Citrus oleocarpa Hort. ex Tan.—This species is the timkat of southern China and yuhikitsu of Japan.  The fruit is small, yellowish-orange, and somewhat oblate.  The base usually has a short radially furrowed neck and the apex is depressed.  The rind is medium-thin, relatively tight but readily peelable, and strongly aromatic.  Flesh color is deeper than that of the rind, the texture is crisp, and the flavor is rich but subacid.  The seeds have light green cotyledons.
      This species is of Chinese origin and is said to have importance on the Chinese mainland, on Hong Kong Island, and on Taiwan.
      6. Citrus reshni Hort. ex Tan. (fig. 4-50)—This species is the chota or billi kichili of India and the Cleopatra mandarin of the United States.  The tree is attractive, round-topped, symmetrical, and thornless, with small, dark-green leaves.  The fruit is orange-red, small, oblate, and highly depressed at the apex, with thin, somewhat rough rind.  The flesh texture is soft and juicy and the flavor is somewhat acid.  Seeds are small, polyembryonic, and have green cotyledons.
      Considered to be native to India and said to have been introduced into Florida from Jamaica sometime prior to 1888, C. reshni is increasingly important as a rootstock in the United States and elsewhere.  It is an attractive ornamental and bears fruit the year round.
      7. Citrus sunki Hort. ex Tan.—The sunki, suenkat or sunkat of South China, which is the sour mandarin (C. reticulate, var. austere) of Swingle's classification (see chap. 3, this work), is a medium-small, upright tree with distinctive pale-green leaves.  The fruit is medium-small, oblate and markedly depressed at both ends, and with basal furrows.  The ring [sic] is very thin, loose, and light yellowish-orange, with a smooth, shiny surface and prominent oil glands.  The rind is strong and spicy with a distinctive aroma.  The flavor is acid, the fruit never becoming edible.  Seeds are medium-large, plump, polyembryonic, and have pale-green cotyledons.
      C. sunki is considered to be native to China and is said to be a widely employed rootstock in China and Taiwan.

Fruits Most Resembling the Mandarins

     Tangors.—Hybrids of the mandarin and orange have been designated tangors (Swingle, Robinson, Savage, 1931).  The few that have been named to date are mandarin-like in most respects and hence fall into this group.
      Varieties commonly referred to as natural tangors include the King and Clementine mandarins and the so-called Temple orange of Florida.  Others which exhibit characters that suggest the likelihood of hybrid parentage include the Campeona, Ellendale, and Ortanique mandarins, the so-called Murcott orange, and the tankan.  In this treatment, however, King is assigned to C. nobilis and, with the exception of Temple, the others mentioned are provisionally placed in the C. reticulata group.  It is to be noted, however, that two of them—Clementine and tankan—are given species standing by Tanaka (1954) as are also a number of other oriental forms such as Iyomikan which he regards as natural tangors.
      Of the so-called natural tangors, Temple is much the most important variety.  While it is obviously a mandarin hybrid, in the opinion of the writer such characteristics as seed monoembryony and pronounced cold-sensitivity of the tree suggest that it may be a natural tangelo of which pummelo rather than grapefruit is one of the parents.  Since the consensus is that it is a tangor, however, it is included here.
      In addition to the natural tangors, there are several synthetic tangors, which are the result of breeding work in California and Florida.  Only one of these—the Umatilla—has any commercial importance, the others remaining experimental.

Dweet
      Fruit medium-large, reddish-orange, globose to oblate-necked, and moderately pebbled.  Rind peels poorly and tends to puff.  Seedy, very juicy, and of rich flavor.  Matures late.  Does not hold well on tree, but good for home use.
      The Dweet tangor, currently on trial in Califomia, is of Mediterranean Sweet orange and Dancy tangerine parentage.  This synthetic tangor resulted from the breeding experiments of H. B. Frost of the University of California Citrus Research Center, Riverside.  It was selected in 1930 and introduced in 1950.

Mency
      Fruit medium-small, reddish-orange, slightly oblate and necked, and faintly pebbled.  Rind peels readily.  Seedy, early ripening fruit of sprightly, acid flavor.  Sensitive to sunburn and does not hold well on tree, but good for home use.
      This synthetic tangor resulted from breeding work by H. B. Frost of the University of California Citrus Research Center, Riverside.  It is of Dancy tangerine and Mediterranean Sweet orange parentage, in which respect it is reciprocal to Dweet.

Temple (fig. 4-51) [Citrus temple Hort. ex Y. Tanaka]
      Fruit medium-large, very broadly obovate to slightly subglobose; sometimes with short, wrinkled, or furrowed neck; frequently with small, sometimes protruding navel; seedy.  Rind color deep reddish-orange; medium-thick; surface somewhat pebbled or rough, and moderately adherent, but readily peelable.  Segments 10 to 12 and axis mainly solid.  Flesh orange-colored; tender, moderately juicy; flavor rich and spicy.  Seed monoembryonic.  Medium-late in maturity.
      Tree of medium vigor, spreading and bushy, somewhat thorny; leaves medium-sized and mandarin-like; productive.  More cold-sensitive than any of the mandarins or oranges.
      Because of its high heat requirement and sensitivity to cold and both rootstock and soil influences, Temple is decidedly limited in its range of commercial adaptation.  In this respect, it is somewhat similar to the King mandarin.  Within its range of adaptation, the fruit is of outstanding attractiveness and quality, but elsewhere it is highly disappointing and commercially worthless.  Temple is at its best in Florida when propagated on sour orange or Cleopatra mandarin rootstocks and grown on the heavier-textured soils.  Satisfactory quality in California is attained only in the hottest of the interior districts.  Elsewhere, Temple is poorly colored and much too tart for most palates.
      The origin and history of this variety are somewhat obscure.  According to Ziegler and Wolfe (1961) and Harding (1959), it originated in Jamaica and came to the attention of a Florida fruit buyer about 1896, who ran across a seedling tree of outstanding quality.  The buyer sent budwood to several friends at Oviedo, Florida, who budded a few trees of this "Jamaica" orange.  About 1900, Allan Mosely, an orchard caretaker in the Winter Park area, is said to have obtained budwood from one of the friends, J. H. King.  Mosely budded a tree in a young orchard under his care which in 1914 came into the ownership of L. A. Hakes.  The following year Hakes called the tree to the attention of a neighbor, W. C. Temple, former manager of the Florida Citrus Exchange, who in turn reported its unusual qualities to his friend and former associate, M. E. Gillett, president of Buckeye Nurseries, a leading citrus nursery.  Exclusive propagation rights were obtained in 1916.  The variety was named and introduced in 1919 and was promoted on a large scale.
      Once its limitations and adaptations became evident, Temple continued to increase in popularity to the point where both acreage and production now exceed that of the Dancy tangerine.  The 1961 crop was nearly 6 million 70-lb box equivalents.  In recent years, Temple has been planted to a limited extent in the Coachella Valley of California, where total plantings were reported to be 796 acres in 1964.

Umatilla
      Fruit medium-large, reddish-orange, and broadly oblate.  Moderately seedy with smooth, medium-thick, moderately adherent rind and hollow axis.  Flesh orange-colored; tender, very juicy; flavor rich but acid.  Seeds monoembryonic and cotyledons green.  Medium-late maturity.
      Tree slow growing, spreading, with considerable resemblance to satsuma; productive.
      Umatilla is a hybrid of satsuma mandarin and Ruby orange resulting from a cross made in Florida in 1911.  This synthetic tangor was named and described by Swingle, Robinson, and Savage (1931).  Although described as a tangelo, from which it is indistinguishable, its parentage is that of a tangor.  It has not achieved commercial importance except as a specialty fruit in Florida.

      Tangelos.—Webber and Swingle (1905) designated hybrids of the mandarin and grapefruit and pummelo as tangelos.  The first crosses giving rise to tangelos were made by these two men in 1897 in Florida.  Currently, a dozen or more tangelos have been named and described.
      As might be expected, the tangelos constitute a highly varied group, exhibiting characters that are both typical of the parents and intermediate between them.  In general, however, those of greatest commercial interest or promise fall into the mandarin-like group.  Some of them produce highly colored, aromatic, distinctive, and richly flavored fruits of good size with thin, smooth, and only moderately loose rinds.  Others exhibit such faults of some of the mandarins as undesirably long necks, puffing of the rind, and excessive seediness.  On the whole, however, the tangelos currently comprise much the most important and promising of the interspecific hybrids of the genus Citrus.  Several of them already have attained commercial importance and one variety, Orlando, achieved production in Florida of more than a million boxes in 1965.
      It has recently been shown that for regular and satisfactory production some of the tangelos require cross-pollination since they are weakly parthenocarpic and benefit from the presence of seed, which they are unable to produce from self-pollination.  A few of them, notably Sampson, reproduce remarkably true to seed since they are highly polyembryonic.
      There are several fruits and varieties of unknown origin that resemble some of the tangelos and are provisionally classified as natural tangelos.  The natural tangelo currently of greatest importance is the Ugli of Jamaica, unless the more popular Temple (herein classed as a natural tangor) is, in fact, a tangelo.
      Treated elsewhere, since they more closely resemble the pummelo are such fruits as the Hassaku andNatsudaidai of Japan, the Attani of India, and the Poorman of Australia.  In addition, some of the synthetic hybrids that bear a greater resemblance to the grapefruit than the mandarin-like fruits are also discussed in a later section.  Tangelo varieties of current importance, promise, or special interest are presented below.

Allspice
      Fruit medium-small, slightly oblate to globose; color orange-yellow; seedy.  Rind thin, slightly pebbled, and rather tightly adherent.  Solid axis; flesh tender and juicy; rich, tart, spicy flavor and aroma.  Midseason in maturity and loses quality if left on tree much past maturity.
      Tree and foliage mandarin-like in appearance.
      Allspice resulted from a cross of the Imperial grapefruit and Willowleaf mandarin made in 1917 by H. B. Frost of the University of California Citrus Research Center, Riverside.  Although the fruit is small, it is attractive because of its rich flavor and spicy fragrance.

Broward
      Broward is a medium-large, midseason fruit of good quality.  It is a hybrid of Duncan grapefruit and Dancy tangerine that was selected in 1912 and released in 1939.  It has never achieved commercial importance.

Clement
      Fruit medium-large, subglobose to slightly oblong; color light orange-yellow.  Few-seeded (monoembryonic); rind pebbled, somewhat wrinkled, comparatively thick, and easily peeled.  Flesh color dull yellow; soft, somewhat gelatinous; flavor mildly sweet.  Medium-early in maturity.
      Tree productive.
      Clement is a hybrid of the Duncan grapefruit and Clementine mandarin produced in Florida in 1914 by W. T. Swingle of the U.S. Department of Agriculture and introduced in 1931.  It has not attained commercial importance.

K-Early
      This variety more closely resembles the grapefruits and pummelos.

Minneola (fig. 4-52)
      Fruit large, oblate to obovate; neck usually fairly prominent; seeds comparatively few, with greenish cotyledons.  Rind color deep reddish-orange; medium-thin, with smooth, finely pitted surface, and moderately adherent (not loose-skin).  Segments 10 to 12 and axis small and hollow.  Flesh orange-colored; tender, juicy, aromatic; flavor rich and tart.  Medium late in maturity.
      Tree vigorous and productive with large, long-pointed leaves.  Less cold-resistant than Orlando.  Cross-pollination recommended for regular and heavy production.  Dancy, Clementine, and Kinnow mandarins appear to be satisfactory pollinators.  Orlando tangelo is cross-incompatible.
      Minneola is a hybrid of Duncan grapefruit and Dancy tangerine produced in Florida by the U.S. Department of Agriculture and named and released in 1931.  Its attractive color, excellent flavor, and low seed content have popularized it in Florida where it is currently of limited commercial importance.  There is increasing interest in its culture in the low elevation desert regions of Arizona and California, where total plantings were reported to be 594 acres in 1964.

Orlando (fig. 4-53)
      Fruit medium-large, broadly oblate to subglobose; without neck; seedy.  Rind orange-colored; thin, slightly pebbled, and fairly tightly adherent (not free-peeling).  Segments numerous (12-14); axis small and hollow.  Flesh orange-colored; tender, very juicy; flavor mildly sweet.  Season of maturity early.
      Tree somewhat similar to Minneola but with distinctively cupped leaves; somewhat more cold resistant; less vigorous; cross pollination recommended for regular and good production.  Dancy, Clementine, and Kinnow mandarins and Teumple tangor are said to be good pollinators.  Minneola tangelo is cross-incompatible.
      Orlando is of the same parentage as Minneola and Seminole—a hybrid of Duncan grapefruit and Dancy tangerine.  Originally it was named Lake, but it was later renamed to avoid confusion.  Its earliness of maturity, good shipping quality, and pleasant flavor made it the outstanding popular tangelo in Florida, where the annual production in 1965 exceeded a million boxes.  In the low elevation regions of Arizona and California, there is increasing interest in its culture.  Total plantings in 1964 consisted of 610 acres.

Pearl
      This variety more closely resembles the grapefruits and pummelos.

Pina
      This Variety more closely resembles the grapefruits and pummelos.

Sampson
      This variety more closely resembles the grapefruits and pummelos.

San Jacinto
      Fruit medium-sized, round or obovate; commonly slightly necked; color orange-yellow; seedy.  Rind relatively smooth, thin, fairly free-peeling; axis hollow.  Flesh color pale orange-yellow; tender, very juicy; flavor sprightly and subacid.  Maturity season early.
      Tree vigorous and productive; leaves small to medium, oval-shaped, and pointed.
      This variety originated at the U.S. Date and Citrus Station, Indio, California, as a seedling of an unnamed tangelo of grapefruit-tangerine (presumably Dancy) parentage from a pollination made bySwingle in Florida in 1899.  Introduced in 1931, San Jacinto has never attained commercial importance.

Seminole
      Fruit medium-large, broadly oblate; color deep reddish-orange; seedy.  Rind somewhat pebbled, thin, and moderately adherent though peelable; axis hollow; Flesh [sic] color rich orange; tender, juicy; flavor sprightly and acid.  Resembles Minneola in appearance, but peels easier and matures later.
      Tree vigorous andproductive; leaves medium-small, rounded, and cupped (like Orlando and Sampson).  Appears to be self-fruitful.
      This variety is of the same parentage as Orlando and Minneola—Duncan grapefruit crossed with Dancy tangerine—and has been planted to a limited extent in Florida.  Seminole has attracted little interest in California, presumably because it is highly seedy and too tart for most palates.

Sunrise (K-Early)
      This variety more closely resembles the grapefruits and pummelos.

Sunshine
      This variety more closely resembles the grapefruits and pummelos.

Suwanee
      This midseason variety produces a large, seedy, deep-orange-colored fruit.  Suwanee is sister to Minneola and Seminole, having originated from a cross of Duncan grapefruit and Dancy tangerine, and has not achieved commercial importance.

Thornton
      Fruit medium-large, oblate to broadly obovate; commonly somewhat necked; light orange-colored; seedy.  Rind pebbled and somewhat rough, medium-thick, flexible, and only slightly adherent (free-peeling); axis mainly hollow.  Flesh color pale orange; very soft and juicy; flavor mildly sweet.  Midseason in maturity.  Puffs badly when overripe.
      Tree hardy to cold, vigorous, and productive; leaves large and long-pointed, resembling sweet orange.
      Thornton originated as a grapefruit and tangerine (probably Dancy) hybrid made by Swingle in Florida in 1899 and was named and released in 1904.  It has failed to attain much commercial importance, although it is grown somewhat as a specialty fruit in Texas and Florida.

Ugli (fig. 4-54)
      Fruit large, broadly obovoid; usually with short, strongly furrowed neck or collar; apex truncated and commonly strongly depressed.  Seeds few and monoembryonic.  Rind color dull yellowish-orange; medium-thick, leathery, moderately rough and bumpy, somewhat ribbed, and loosely adherent.  Segments about 12 and axis large and open.  Flesh orange-colored; tender, very juicy; flavor rich and subacid.  Maturity season late.
      Tree reported to be upright-spreading and mandarin-like in appearance.
      According to Webber (1943), the rather unusual name for this natural tangelo is said to have been given to this unattractive but delicious fruit in the Canadian market which first received it.  It was referred to as the "Ugly" citrus fruit.  Soon thereafter, the name Ugli became the copyrighted trademark of G. G. R. Sharp, the principal and for some time the only Jamaican exporter.
      From the information he was able to obtain, Webber (1943) concluded that Ugli originated as a chance seedling of unknown parentage near Brown's Town, Jamaica.  It came to notice in 1914 and was propagated by F. G. Sharp at Trout Hall and first exported about 1934 by his son, G. G. R. Sharp.  It is obviously a hybrid with characters that suggest mandarin and grapefruit parentage, hence Webber provisionally classed it with the tangelos.  Partly because of the monoembryony exhibited by the seeds, it is the opinion of the writer that pummelo is the parent in question rather than grapefruit.
      While the fruit is unattractive, its shipping and eating quality have given it a high reputation in Canadian and English markets and its production is increasing in Jamaica.

Webber
      Webber is a medium-sized, flat, thin-skinned orange-colored fruit of good quality.  The variety is of Duncan grapefruit and Dancy tangerine parentage and was selected in Florida in 1909 and introduced by the U.S. Department of Agriculture in 1932.  It has never achieved commercial importance.

Wekiwa
      This variety more closely resembles the grapefruits and pummelos.

Yalaha
      Fruit medium-sized, oblate; base slightly depressed and somewhat furrowed; orange-colored; seedy; Rind [sic] pebbled and somewhat rough, medium-thick, slightly adherent; axis large and hollow.  Flesh color pale orange; tender, juicy; flavor sprightly subacid.  Late in maturity.
      Tree vigorous and productive; leaves oval-shaped and pointed, resembling sweet orange.
      Yalaha is a Duncan grapefruit-Dancy tangerine hybrid made by the U.S. Department of Agriculture in Florida in 1911 and introduced in 1931.  The variety has not achieved importance.

      Other Mandarin-Like Fruits.—In addition to the tangors and tangelos, however, there are certain other citrus fruits of the Orient which have rather obvious resemblances to the mandarin.  Principal in horticultural importance among these are the Calamondin, Iyo, and Rangpur.

Calamondin (Citrus madurensis Loureiro)
      Fruit very small, oblate to spherical; apex flattened or depressed.  Rind color orange to orange-red; very thin, smooth, and finely pitted, easily separable only at maturity; sweet and edible.  Segments about 9 and axis small and semi-hollow.  Flesh orange-colored; tender, juicy, and acid.  Seeds few, small, plump, polyembryonic, and with green cotyledons.  Fruit holds on tree remarkably well.
      Tree of medium vigor, highly productive, upright and columnar, nearly thornless; leaves small, broadly oval, and mandarin-like.  Strongly cold-resistant.
      The mandarin-like Calamondin (fig. 4-55) is the Calamonding of the Philippines, the szukai-kat of southern China and Taiwan, the tôkinkan and shikikitsu of Japan, the djerook kastoori of Java, and the hazara of India.
      There has been some doubt about the status of this fruit.  Swingle recognized it as a valid species in 1914, but later failed to give it specific rating (see chap. 3, this work).  Tanaka for some time retained its specific rank in what he designated as the Mitis subgroup.  More recently, Tanaka (1954) has classed it as Citrus madurensis Loureiro.
      Undoubtedly of Chinese origin, this fruit was early and widely distributed throughout the Orient, including Indonesia and the Philippines, where the earliest descriptions were made.  Although mandarin-like in most respects, it has similarities with the kumquat and sometimes has been confused with that fruit, particularly in India and Ceylon.  Indeed, Swingle (1943, p. 357) considered it to be a natural hybrid between a sour mandarin and some kumquat.
      The Calamondin has little economic importance for the fruit but is widely used as an ornamental in Florida and California.  It is especially attractive as a potted or tubbed plant in fruit and currently is extensively grown and shipped to the population centers of the United States for use as a winter house plant.  It also makes an excellent rootstock for the oval or Nagami kumquat, when grown for similar purposes.  Peters, an attractive, variegated-leaf form is grown somewhat in California, primarily for landscape use.

Iyo (Iyomikan)[Citrus iyo Hort. ex Tan.]
      Fruit medium-sized, subglobose to broadly obovoid; apical end shallowly depressed.  Rind thick, lightly pitted, tender, and easily separable; deep orange-colored.  Medium seed content (some with pale green cotyledons).  Central column broadly open and segments about 10.  Flesh orange-colored; tender, very juicy, sweet; flavor rich and pleasant.  Midseason in maturity.
      Tree vigorous.
      The Iyo is believed by Tanaka (1954) to be a natural tangor and was found about 1883 by M. Nakamura in Obu-gun, Yamaguchi Prefecture, Japan.  First described as Anado mikan in 1892, it was early introduced into Ehime (formerly Iyo) Prefecture, where it was widely planted and came to be known as Iyo.  While attractive in appearance and of good flavor, it loses quality rapidly in storage and on the tree.  As a result, it has been little planted in recent years.  Currently, its culture is limited largely to the vicinity of the city of Matsuyama.

Rangpur (Citrus limonia Osbeck)
      Fruit small to medium in size, variable in form but mainly depressed globose to round or broadly obovate; sometimes with furrowed collar or low neck; often with short nipple partially or entirely surrounded by a shallow furrow.  Rind color yellowish to reddish-orange; thin, and moderately loose, with surface minutely pitted and smooth to slightly rough.  Segments 8 to 10, loosely adherent; axis large and hollow at maturity.  Flesh orange-colored; tender, juicy, and strongly acid.  Seeds fairly numerous, small, highly polyembryonic, and with light green cotyledons.  Fruit holds on tree for a long period.
      Tree usually vigorous and productive, medium-sized, spreading and drooping, with slender twigs, comparatively few and small thorns; foliage dull-green and mandarin-like, and new shoot growth lightly purple-tinted.  Flowers small and mandarin-like and buds and petals deeply purple-tinged.  Hardy to cold.
      The description of the Rangpur given above is generalized.  Several clonal varieties of this mandarin-like fruit have been selected and named and a comparatively wide variation exists in fruit characters in regard to form, color, smoothness and adherence of rind, and acidity and flavor.
      Common names used for the fruit include Rangpur in India, Canton lemon in South China, hime lemon in Japan, cravo lemon in Brazil, Japanche citroen in Java, and Rangpur lime or mandarin-lime in the United States.  Other Indian names include Sylhet lime, surkh nimboo, sharbati and marmalade lime.  The name lime employed in connection with this fruit is misleading and should be avoided since the only similarities between it and the true limes are that both have small flowers and because they are both highly acid can be used as substitutes.
      Resemblances between the Rangpur and mandarin are obvious and numerous, and for this reason it is best included under the mandarin-like fruits.  The rough lemon and Rangpur also exhibit rather close similarities and important differences.
      Almost certainly of Indian origin, the Rangpur early spread throughout the Orient and to the East Indies.  According to Webber (1943), it was introduced into Florida in the late nineteenth century by Reasoner Brothers of Oneco, who obtained seed from northwestern India.  The Rangpur is of horticultural importance primarily as a rootstock both in the Orient and South America and as an ornamental.  The three most important forms of the Rangpur are discussed below.
      Kusaie.—Generally referred to as the Kusaie lime, presumably because of the yellow color and high acidity of the fruit, Kusaie should be properly regarded as a yellow-fruited form of the Rangpur and therefore called the Kusaie Rangpur.  The tree is indistinguishable from other Rangpurs and the fruit differs significantly only in color.
      Almost certainly this form or variety originated in India, for it markedly resembles the nemu-tenga of Assam (Bhattachariya and Dutta, 1956) and is indistinguishable from a promising rootstock used in trials in Punjab State and West Pakistan called nasnaran, but which the writer identified as Kusaie Rangpur.  According to Webber (1943), this fruit was introduced into Hawaii from Kusaie Island, of the Caroline group, by Henry Swinton in 1885 and thence into the United States by Webber in 1914.  It seems first to have been described by Wilder (1911, p. 86).
      Kusaie is said to have local importance as an acid fruit in the Hawaiian Islands.  Elsewhere in the United States it is a collection item or oddity.
      Otaheite (fig. 4-56).—Usually referred to as the Otaheite orange, this fruit should be properly regarded as an acidless or sweet form of the Rangpur and therefore should probably be called the Otaheite Rangpur.  The tree is similar to the common Rangpur but less vigorous and hence dwarfed.  It is almost thornless and the purple coloration on the new shoot growth is more intense.  Likewise, the fruit is similar but somewhat smaller, more commonly necked, contains fewer normal seeds (often none), and is insipidly sweet from lack of acid.
      Since an acidless form of the Rangpur is known in India, this fruit doubtless originated there.  However, the first known reference to it (Risso and Poiteau, 1818-22, p. 66) described it as Citrus otaitense, a small orange from Otaite (Tahiti) brought to Paris from England in1813.  How or when it reached the United States is not known, but it was listed as a potted ornamental in the 1882 nursery catalog of R. J. Trumble of San Francisco, California (Butterfield, 1963).  Easily propagated from cuttings, as are all the Rangpur, it is extensively grown in the United States as a potted ornamental, primarily as a winter house plant.  Several unnamed clones are recognized.
      Rangpur (fig. 4-57).—The clone or clones grown in the United States correspond with the general description given above.  It seems probable that one principal clone is involved, since this fruit is highly polyembryonic and reproduces remarkably true from seed.  As grown elsewhere, apparently there are several rather similar clones.  This appears to be the case in the Orient (Hodgson, Singh and Singh, 1963) and is suggested bythe observation of minor differences in a collection of a dozen or more accessions from widely separated sources assembled in California.  The differences seem to be concerned principally with the form of the fruit and nature of the rind surface.
      In the United States (particularly in California), the Rangpur is widely used as a hardy, dooryard fruit and ornamental and as a potted or tubbed plant.  It is especially well adapted for such uses since it propagates readily from cuttings and is easily dwarfed when the roots are confined.  Outside the United States, its use seems to be principally as a rootstock.  Primarily because of its tolerance to the tristeza virus and resistance to soil-borne diseases, it is a rootstock widely employed, especially in Brazil where it is known as the cravo lemon.  When employed for such use, however, the scion materials must be free from exocortis virus, for the Rangpur as a rootstock is severely affected by that disease.

PUMMELOS AND GRAPEFRUITS
      The pummelos, or shaddocks, and the grapefruits exhibit so many resemblances in both tree and external characters that close botanical relationship is obvious.  Indeed, most systematists have either placed them in the same species or classed the grapefruit as a subspecies or botanical variety.  The differences are more basic and numerous than appear at first glance, however, and separation into different species seems clearly justified.  Nevertheless, it cannot be denied that there are pummelos which so closely resemble grapefruits that it is difficult to separate them with accuracy on any basis other than the presence or absence of polyembryony.
      The principal differences between the two groups are set forth in the list of comparisons on page 534 adapted from Webber (1943).¹⁷
      The pummelos as a group exhibit a very much greater range of variation in characters than do the grapefruits.  Some of them are comparatively small trees, whereas others are among the largest of citrus trees.  Some exhibit a marked degree of pubescence on the young growth, whereas others are scarcely, if at all,

Pummelo (Citrus maxima [Burm.] Merrill, C. grandis [L.] Osbeck or C. decumana L.)

      It seems reasonably certain that the pummelo is indigenous to the Malayan and East Indian archipelagos, whence it early spread to South China and India and thence followed the same path as most of the other citrus fruits to Europe and America.  According to Tolkowsky (1938), it was mentioned in Palestine in 1187 A.D. and in Spain about the same time.  Ferrari (1646) described and illustrated several kinds in Italy.  According to Webber (1943), it was mentioned and described in Jamaica in 1696 under the name shaddock and in 1707 an account of its introduction reported that seed of this fruit had been brought to Barbados by a Captain Shaddock, in command of an East Indian ship (see chap. 1, footnote 6).  The name, shaddock, has persisted ever since in the West Indies and the United States.  Pummelo is the preferred name, however, and appears to have been derived from pompelmoes or pomplemoose, names given to it by the Dutch in the East Indies (Indonesia).  In French it is the pamplemousse, in Italian the pompelmo, in Spanish the pampelmus, and in Japanese the buntan or zabon.  The large size of the fruit is reflected in the species designations most commonly employed (maxima, grandis).
      While most of the pummelos are inferior or worthless as fresh fruits, there are superior kinds and varieties that are highly prized in the Orient and grown commercially.  The principal centers of such production occur in southern China, Thailand (Siam), Vietnam (Indo-China). [sic] Malaysia (Malaya), Indonesia, Taiwan (Formosa), and Japan.  The distribution of superior varieties and the environmental conditions under which good eating quality is attained appear to be restricted however, and elsewhere in the Orient the fruit is used primarily for culinary and medicinal purposes.  In other parts of the citricultural world, the pummelo has remained a collection item or novelty of interest principally for breeding purposes because of its giant-sized fruits.
      As previously noted, the pummelos comprise a highly variable group.  Some of them approach or equal the grapefruits in vigor and size of the tree, but many of the commercial varieties are much less vigorous and smaller, although apparently equally resistant to neglect.  In the limited area where comparisons have been possible, pummelos have shown considerably less cold tolerance than the grapefruits.  While in heat tolerance they are comparable, the pummelos exhibit a much wider range in heat requirement, some varieties maturing earlier than any of the grapefruits and others attaining acceptable quality only in regions of very high total heat.
      The pummelos of highest repute in the Orient appear to be grown in reclaimed coastal marsh areas subject to the flow of brackish tidal waters which are high in salt content.  This has given rise to the belief that the presence of salt is related to, if not responsible for, the distinctive quality of the fruit.  Groff (1927) has reported obtaining confirmatory evidence of this belief from tests of salt application to the soil about trees.  Whatever the facts may be, it is true that production of good quality pummelos is highly restricted in the Orient and that the best varieties have apparently failed to develop equal quality inthe United States or Mediterranean basin.  Only a few varieties have produced fruits of reasonably good edibility in the United States, primarily in Florida and the hottest interior areas of California and Arizona.  None of these fruits has proven as acceptable to most palates as a good grapefruit.
      Another distinctive feature of pummelo culture is the fact that commercial propagation in most parts of the Orient is by means of air-layerage (marcottage) rather than graftage.
      Because of firmer flesh texture and lower juice content, many of the pummelos, particularly most of the highly reputed varieties, do not lend themselves to serving in the manner employed for the grapefruit—spooning the flesh from the cut fruit or juicing.  After peeling the fruit, the segments are separated and the carpellary membranes—commonly already burst at the suture—are easily pulled away from the mass of pulp-vesicles (juice sacs).  Unlike the grapefruit, this can be accomplished without rupturing the walls and the resultant escape of juice and soiling of the hands.  For table use, the pulp-vesicles are shelled out into dishes and served with or without sugar.  None of the major varieties exhibit the trace of bitterness characteristic of grapefruits, although there are bitter pummelos.
      Many if not most of the commercially important varieties of Thailand, South China, and Taiwan belong to a highly distinctive group, obviously of common ancestry and presumably of Siamese origin.  The trees are small to medium-small, round-topped, and drooping in contrast with the medium to large, broad-spreading trees of most pummelos.  The branches are less thorny, the twigs thicker and more densely pubescent, and the leaves more round-pointed.  The flowers are larger and more woody in texture.  The surface of the young fruits exhibits pubescence which is often retained to maturity.  The rind of the mature fruits is less spongy and the flesh firm and crisp with tough carpellary membranes and juice sac walls.  The flesh is hence much less juicy than most other pummelos.  Varieties in this group include Kao Pan and Kao Phuang of Thailand and Mato of China, Taiwan, and Japan.
      With respect to fruit characteristics, the pummelos fall into both of the natural groups found in the grapefruits and some of those which occur in the sweet oranges.
      Most pummelos fall in the common or ordinary group, the fruits of which are highly variable in nearly all respects except pigmentation and acid content.  They are all non-pigmented, moderately to highly acid, and typically seedy, although there are varieties that are virtually seedless or nearly so in the absence of cross pollination (Soost, 1964).
      Similar to the common pummelos in all respects except that they are virtually devoid of acid are the acidless or non-acid pummelos, a group analogous to the sugar oranges.  Comparable analyses of acid content and sugar-acid ratios for a clone of this group and several common pummelos have been reported by Soost and Cameron (1961).  Results were as follows: for an acidless clone, 0.08 to 0.10 per cent acid content and ratios of 126-151.3 to 1; for four common clones, 1.02 to 1.93 per cent acid content and ratios of 5.6-11.4 to 1.
      The pigmented pummelos are similar to the common pummelos except for the pigmentation caused by the carotenoid lycopene, which ranges from light pink to deep red.  Some of them are highly attractive and excellent in flavor.
      That there is a pummelo group somewhat comparable with the navel oranges is suggested by Reinking's (1929) report of a so-called double pummelo in the Molucca Islands.  From his description, the structure of the fruit is similar to that of the double-fruit navel orange.
      As would be expected, the varieties of commercial importance consist of clones of the common and pigmented groups, the fruits of which are oblate, round, or broadly pyriform, with relatively thin rinds, and sweet to mildly acid in flavor.  The writer must of necessity rely upon the literature, which is limited, in describing the characteristics of some of the varieties.

      Common Group Varieties.—The major varieties of the common group of pummelos are described below.  Among the introductions received in California from the U.S. Department of Agriculture during the 1930-35 period, however, there are several varieties, the history of which has been lost, which are equal or superior to any of the major varieties.  Only one, Kao Kuan (Ruan) Tia is mentioned by Groff (1927) and hence known to be of Siamese origin.  The California introduction corresponds rather well with his description, although the original materials consisted of seedlings.  The other varieties are Karn Lau Yao, Pin Shan Yao, Pong Yao, and Tau Yao, all presumably of Chinese or Siamese origin.  All are medium-large to large productive trees with fruits that are broadly obovoid to short-pyriform.  The fruits have medium-thin to medium rinds and are juicy and of good to excellent flavor.

Banpeiyu (fig. 4-58)
      Fruit very large (one of the largest), subglobose to spheroid; seedy.  Light yellow.  Rind thick; surface smooth and tightly adherent.  Segments numerous (15-18); axis large and solid; carpellary membranes thin but tough.  Flesh color pale yellow; tender and juicy; flavor excellent, a pleasant blend of sugar and acid.  Medium-late in maturity but stores well for several months longer.
      Tree very vigorous, spreading and large; leaves large and broadly winged; twigs, new shoot growth, petioles, and lower surface of leaves pubescent.
      Banpeiyu is almost certainly the variety known as Pai You (Yau)on Taiwan.  The variety is of unknown Malayan origin and was introduced into Formosa (Taiwan) in 1920, named in 1925, and taken to Japan soon thereafter.  It develops high quality fruit only in the hottest regions of southern Japan.  Among pummelo varieties, it currently ranks first in Japan and second on Taiwan.

Hirado (Hirado Buntan)
      Fruit large, oblate, slightly depressed at both ends; seedy.  Color bright yellow when mature.  Rind medium thick; surface smooth and glossy; tightly adherent.  Segments numerous and carpellary membranes thin but tough.  Flesh light greenish-yellow; tender and moderately juicy; flavor a pleasant blend of sugar and acid with trace of bitterness.  Medium-early in maturity but stores well.
      Tree vigorous, medium-large; leaves large, thick, and broadly winged.  More cold-resistant than most pummelos.
      This variety originated as a chance seedling in Nagasaki Prefecture of Japan, was named and introduced about 1910, and is currently second in importance there.

Kao Pan (Kao Panne)
      Fruit medium-large, subglobose to spherical; apex slightly depressed; seedy if open-pollinated, but otherwise not (Soost, 1964).  Lemon-yellow (deeper than most) at maturity.  Rind medium-thick; faintly pebbled with prominent oil glands; tightly adherent.  Segments numerous (12-15); carpellary membranes thick and tough; axis medium-small and solid.  Juice sacs large, fleshy, easily separable, and moderately juicy.  Flavor sweet and mildly acid.  Early in maturity.
      Tree medium-small, round-topped and drooping, nearly thornless; leaves medium-large and round-pointed; twigs and new shoots densely pubescent; large, woody flowers.
      According to Groff (1927), Kao Pan is one of the most highly reputed varieties of Thailand and almost certainly originated in the Nakorn Chaisri district.  Groff considers Nakorn to be a synonym.  In California, however, Nakorn more closely resembles Kao Phuang; both clones were received from the U.S. Department of Agriculture in 1930.  The reason for this discrepancy doubtless resides in the fact that the original introductions into the United States were budded plants in the case of Kao Pan and Kao Phuang and seeds in the case of Nakorn.

Kao Phuang
      Fruit large, broadly pyriform with distinct neck; apex even or slightly depressed; seedy if open-pollinated but otherwise not (Soost, 1964).  Lemon-yellow at maturity.  Rind medium-thick; surface smooth, glossy; less tightly adherent than Kao Pan.  Segments numerous and easily separable; carpellary membranes moderately thick and tough; axis small and solid.  Vesicles large, easily separable, and firm but juicy.  Flavor good (more acid than Kao Pan).  Medium-late in maturity and holds well on tree with retention of quality.
      Tree similar to Kao Pan, but somewhat more vigorous and upright.
      Groff (1927) reports that Kao Phuang is recognized as one of the two best varieties in Thailand, some persons preferring it to the famous Kao Pan.  In California, its flavor is clearly superior.  In the collections at the University of California Citrus Research Center, Riverside, one of several clones received under the name Siamese is indistinguishable from Kao Phuang, and is probably identical.

Mato (Mato Buntan) (fig. 4-59)
      Fruit medium-large, broadly obovoid to pyriform; seedy.  Light-yellow at maturity.  Rind medium-thick; surface coarsely pitted, pebbled from protuberant oil glands; tightly adherent.  Segments numerous (12-16) and carpellary membranes thin but tough.  Flesh color light greenish-yellow; crisp, somewhat tough, lacking in juice; flavor sweet (mildly acid), sometimes with trace of bitterness.  Early in maturity.
      Tree dwarfed and small, round-topped and drooping; twigs and shoot growth short, thick, and densely pubescent; leaves large, thick, and pubescent on the lower surface.
      This variety is said to have been taken from South China to Taiwan about 1700 and thence—but much later—to Japan.  Mato is currently first in importance among pummelo varieties in Formosa and ranks third in Japan.  From the description, it is obviously of the small-tree Siamese type and has numerous resemblances to such varieties as Kao Pan and Kao Phuang.
      Mato is the seed parent of the comparatively new and promising Tanikawa buntan, the pollen parent of which is presumed to be the Japanese Sanbôkan.  That it is of hybrid origin is strongly suggested by the facts that (1) the tree is more vigorous, conspicuously upright in growth habit and appreciably more cold resistant, and (2) the fruit is smaller, with much thinner rind and deeper color, and the flesh is tender, juicy, and of excellent flavor.  Moreover, the number of segments is about a third fewer and the season of maturity late.
      Tanikawa originated at the Horticultural Research Station, Okitsu, Japan, from pollinations made during the period of 1913 to 1925 and was named for the originator, T. Tanikawa.  It has been planted to a limited extent in Kagoshima Prefecture, but it is not yet grown extensively.

Moanalua
      See under Tahitian.

Nakorn
      See under Kao Pan.

Siamese
      See under Kao Phuang.

Tahitian (Moanalua)
      Mention should be made of the so-called Tahitian grapefruit because of its distinctive characteristics and high quality.  This agreeably-flavored fruit is in reality a thin-rinded, highly juicy pummelo.  The seeds are monoembryonic and otherwise typical of the pummelo and the shoot growth is much more pubescent than any of the grapefruits.  The faintly amber flesh color suggests the possibility that it may be lightly pigmented under conditions more favorable for color development.
      The origin of Tahitian is obscure but it is believed to have developed in Tahiti from seed from Borneo whence it was taken to Hawaii.  The variety is of local and limited importance only, but is highly reputed for its excellent quality.

Tanikawa
      See under Mato.

      Pigmented Varieties.—Major pigmented varieties of the pummelo are described below.  Numerous other pink or red-fleshed clones are known to exist in the Orient but information is not available concerning their importance or characteristics.

Chandler
      Fruit medium in size, oblate to globose; seedy.  Rind medium-thick, smooth, and sometimes faintly pubescent.  Flesh firm but tender, moderately juicy; flavor intermediate between acidless and moderately acid parents.  Early in maturity and stores well.
      Chandler is a synthetic variety, recently described and released by the University of California Citrus Research Center, Riverside (Cameron and Soost, 1961).  It is pink-fleshed like the pollen parent, Siamese Pink, but otherwise intermediate in characteristics between it and the seed parent, Siamese Sweet.

Egami
      See under Ogami below.

Ogami
      One of the better varieties in Florida is Ogami, which corresponds sufficiently well with the description of the Japanese Egami buntan to warrant the conclusion that they are probably the same.  The fruit is large and broadly oblate, with a moderately thick, smooth rind and numerous seeds.  The flesh is moderately firm, juicy, and of good flavor.  In Florida, rind pigmentation is very faint or lacking, but the flesh is deep pink (almost red) extending into the albedo.

Pandan Bener
      Ochse (1931) describes the Pandan Bener as one of the two best varieties in the Batavia district of Java.  The fruit is oblate to globose in form, red-fleshed, pleasantly flavored, and sweet with a slight amount of acid.  The tree is large and vigorous, but less productive than the Pandan Wangi (see below).

Pandan Wangi
      This variety is ranked with Pandan Bener as one of the two outstanding varieties of the Batavia district of Java (Ochse, 1931).  The red-fleshed fruit is oblate to globose in form, has a slight acid content, and is pleasantly sweet flavored.  The tree is described as vigorous, large, and productive.

Siamese Pink (Siam)
      Fruit large, broadly obovate to short pyriform with shallow depression at apex; nearly seedless.  Light yellow at maturity in California, but probably pink-tinted in semitropical climates.  Rind medium-thick; surface smooth; tightly adherent.  Segments numerous and carpellary membranes moderately tough, but commonly split open at axis at maturity.  Flesh coarse-grained, pink-tinged; very juicy; flavor grapefruit-like (subacid with trace of bitterness).  Late in maturity.
      Tree vigorous, very large, and spreading; leaves typical—broad-pointed; twigs and shoot growth faintly pubescent.
      This clone, which was received by the Citrus Experiment Station, Riverside, from the U.S. Department of Agriculture in 1929 under the name Siamese Pink (CES 2246) corresponds ell with the variety Siam, named and described by Wester (1917).  According to Wester, it was introduced into the Philippine Islands in 1913.  In California, when fully ripe it is clearly one of the best in flavor, although sometimes it has a trace of bitterness.

Thong Dee
      Fruit medium-large, very broadly obovoid to oblate; apex slightly depressed; seedy.  Light yellow at maturity.  Rind medium-thin, smooth, and tightly adherent.  Under favorable conditions both albedo and flesh are pink-tinged, the latter in streaks.  Carpellary membranes thin but tough and readily separable from pulp.  Vesicles large; juice plentiful; flavor good.  Midseason in maturity.
      Tree vigorous and large.
      The description of this Siamese variety was adapted from Groff (1927) and does not correspond with the clone received in California in 1930 from the U.S. Department of Agriculture.  Groff states, however, that the original materials sent to the United States consisted of seeds and seedlings.  The clone in the California collections produces non-pigmented fruits of indifferent quality.  That grown in Florida seems to be different since it is reported to correspond with Groff's description.

      Sweet or Non-Acid Varieties.—At least two clones of the non-acid (hence sweet) pummelo group are known and there are doubtless others.
      The clone known in the United States (fig. 4-60) was introduced by the U.S. Department of Agriculture in 1930 and was received by the Citrus Research Center, Riverside, California, under the name Siamese Sweet (CES 2240).
      The tree is typical of the Siamese group in all respects—dwarf and drooping, with round-pointed leaves and densely pubescent twigs and new shoot growth.  The fruits are oblate to broadly obovoid, with large, crisp, easily separable juice sacs lacking in juice, and insipidly sweet with a trace of bitterness.  Siamese Sweet is of horticultural interest primarily as a curiosity and also because it is the seed parent of the recently released Chandler variety (Cameron and Soost, 1961).
      The other non-acid clone is the Ama or Mikado buntan of Japan, which Y. Tanaka has described as the botanical variety dulcis (Tanaka, 1948).  From his description and illustration, the tree is indistinguishable from Siamese Sweet but the fruit is subglobose to spherical.

Grapefruit (Citrus paradisi Macfadyen)

      The origin and significance of the name of this important fruit are obscure.  According to Webber (1943), who made a comprehensive search of the literature, the earliest recognizable mention of grapefruit occurred in Barbados (West Indies) in 1750 under the name "forbidden fruit," from which the species designation, paradisi, was assigned in 1830.  A few years later it was referred to in Jamaica as the "forbidden fruit or smaller shaddock." The first known use of the term grapefruit occurred in 1814, also in Jamaica, in which it was referred to as a special and smaller kind of shaddock whose flavor somewhat resembled that of the grape.  It seems more likely, however, that the name was derived from the fact that the fruits commonly occur in small clusters rather than singly, as with most shaddocks (pummelos).  Early in the present century, the name pomelo was proposed and for a time was used by American horticulturists.  It was not accepted by the industry, however, and has now virtually disappeared.  The Spanish name is toronja.
      Almost certainly, the grapefruit originated in the West Indies, for it is not described in the old literature and was not known in Europe or the Orient until after its discovery in the Western Hemisphere.  That it was derived from the pummelo is certain, but whether by somatic mutation or natural hybridization is not known.  It is the opinion of the writer, based on observations of numerous natural hybrids of the pummelo in northeastern India, Sikkim, and eastern Nepal, that the grapefruit originated as a natural hybrid.
      The attractive qualities of the grapefruit were early recognized and even prior to the time it was first referred to by that name in the literature it was said to be common in Jamaica and was probably known throughout the West Indies.  It remained for Florida, however, to introduce this excellent fruit to the American consumer and to develop a commercial industry.  This fact explains why, with the sole exception of Redblush (Ruby), all the grapefruit varieties of commercial importance have originated in Florida and apparently trace back to the original introduction.
      According to Ziegler and Wolfe (1961), the introduction in Florida was made by Count Odette Phillippe, a Frenchman, who settled near Safety Harbor on Tampa Bay in 1823 and brought with him seeds or seedlings of the grapefruit and other citrus fruits from the Bahama Islands.  Webber (1943) states that the introduction occurred about 1809 and quotes a pioneer grower of that district who in 1892 reported that the citrus materials in question were said to have come from Cuba.  Whatever the facts may be, it was from this introduction that the commercial grapefruit industry of the world developed.  The Florida commercial industry, however, had its beginning about 1885, by which time trial shipments made to Philadelphia and New York bad met with a favorable reception and demand for nursery trees was developing.  Commercial production elsewhere was not undertaken until some decades later in California, Arizona, and Texas and more recently in other parts of the citricultural world.
      Because of the phenomenal development of the industry in Florida and Texas, within a half-century from the beginning of its commercial culture the grapefruit attained the status of a major citrus fruit.  With a production exceeding 52 million boxes in 1965, the grapefruit closely approaches the mandarins in importance and exceeds the lemon, comprising about 10 per cent of the world production of citrus fruits.  The United States is much the largest producer, accounting for about 80 per cent of the world crop (mainly in Florida), followed by Israel, the West Indies (including Jamaica and Cuba), Argentina, and South Africa.  Grapefruit is also grown to a limited extent in Spain, Morocco, Australia, Algeria, and Cyprus.
      The grapefruit tree is vigorous and under favorable conditions is one of the largest citrus trees, requiring more space than any other.  Its resistance to heat is outstanding and in cold tolerance it closely approaches the sweet orange.  Like the bitter orange, it withstands neglect to a considerable degree.  As a consequence, the grapefruit exhibits a wide range of climatic adaptation.  Its very high heat requirement for the production of fruit of good quality, however, restricts its commercial culture to hot climates.  This requirement coupled with its marked heat resistance render the grapefruit almost equally well adapted to hot desert and humid semitropical or tropical climates, in which respect it is approached only by some of the mandarins.
      Effects of the climatic environment on the characteristics of the fruit are striking and important.  Under desert conditions the color is brighter and deeper and the flavor more sprightly and pronounced than in humid climates, accompanied by somewhat smaller size, less oblate form, and lower juice content.  The differences are sufficiently great to constitute a natural trademark and to provide the markets with fruits for a wide variety of tastes and preferences.
      Because of its refreshing flavor and the mild bitterness contributed by the glucoside naringin, the fresh grapefruit is unexcelled as a breakfast fruit served either in halves or as juice.  It is also widely used as a salad fruit and to some extent for dessert.  Because of overproduction which occurred in the 1920's, it early received attention from the processors with the result that the first commercially successful canned citrus products were single-strength grapefruit juice and fruit segments (hearts).  Improved over the years, these products have achieved consumer acceptance and industry importance.  During the 1961-62 season some 9 million boxes (90-1b) were used for single-strength canned grapefruit juice and 3 million for canned grapefruit sections.  While important, the impact of the recent frozen concentrate juice process on the grapefruit industry has been much less spectacular than occurred with the orange industry.  Thus, the utilization of grapefruit for this excellent product in 1961-62 amounted to only 2.7 million boxes and up to 1966 never exceeded 4.5 million boxes.  During the decade ending in 1966, on the average slightly less than half of Florida production was used for processing.
      Essential oil and pectin are the principal byproducts obtained from the rind.  Grapefruit seed oil is an interesting byproduct of minor importance.
      The grapefruits fall into two natural groups—the common and pigmented grapefruits—which are similar to two of the four groups found in the sweet oranges.  On the basis of season of maturity, they may be early, midseason, or late.  In general, the seedy varieties are early or midseason and the seedless varieties are late in maturity.  Where legally permissible, however, such as in Florida and certain foreign countries, these differences virtually can be eliminated by the use of arsenical sprays, which act to reduce normal development of acidity.

      Common Grapefruit.—The common or ordinary grapefruit is increasingly referred to in the trade as the white grapefruit to distinguish it from the pigmented varieties.  Typically, the trees are vigorous, large, and very productive and the fruit is seedy and rich in flavor.  From the early seedling plantings in Florida, all of which trace back to the original introduction, numerous selections were made many years ago and named as varieties.  The most important of these is Duncan, which was a seedling from a tree in the original planting.  Many if not most of these early named varieties have proved to be indistinguishable and doubtless represent the same parental clone.  In the markets of the United States, the fruit from seedling trees and some of these varieties, of which there remains considerable acreage, is usually sold under the name Florida Common.
      Connoisseurs generally agree that the flavor of the seedy fruits is richer and more pronounced than that of the so-called seedless varieties.  Since they also mature earlier and exhibit better section stability in canning, processors prefer the seedy fruits and in recent years extensive plantings of such varieties have been made.
      The first commercially seedless grapefruit (with few or no seeds), later named Marsh, became available in 1889 and because of that highly desirable characteristic within a few decades attained dominance in Florida and became the leading grapefruit variety of the world, a status it has retained ever since.  More recently, at least two other seedless varieties of the common grapefruit type have been found, namely Davis in Florida and Cecily in South Africa, neither of which has attained much commercial importance.
      Among the early named varieties are several such as Royal and Triumph, the fruits of which differ from the usual seedy grapefruit, as typified by Duncan, in that they are smaller, less oblate in form, sometimes with persistent style, somewhat deeper in color, less pronounced in flavor and bitterness, and usually earlier in maturity.  The possibility has been suggested that they may be natural grapefruit-orange hybrids (orangelos).  None has attained commercial importance.

      Major Common Grapefruit Varieties.—Of common grapefruit varieties, only Marsh and Duncan are currently being planted on an important commercial scale, the former in all parts of the world where grapefruit is grown and the latter principally in Florida and primarily for processing.  The most important varieties are described below.

Bowen
      See under Duncan below.

Duncan (fig. 4-61)
      Fruit large, oblate to globose or broadly obovate; basal furrows short and radiating; areolar ring faint; seedy.  Color pale to light yellow.  Rind medium-thick and surface smooth and even.  Flesh color buff to chamois-colored; tender, very juicy; flavor pronounced and excellent.  Medium-early in maturity.
      Tree vigorous, large, very productive, and reputed to be probably the most cold-resistant.
      This variety represents the oldest grapefruit clone grown in Florida, though it was not named and introduced until about 1892.  As near as can be determined, the parent seedling tree was planted around 1830 near Safety Harbor, on the Pinellas Peninsula, Florida.  The seed came from a tree in the original planting made by Count Odette Phillippe, who is credited with having brought the grapefruit to Florida from the West Indies.  It was named for the introducer, A. L. Duncan of nearby Dunedin.
      Since the grapefruits are highly polyembryonic and all varieties and seedlings in Florida trace back to the planting which contained the seed parent of Duncan, the probability is good that many, if not most, of them represent the same clone.  Certainly many of the early named varieties are indistinguishable from Duncan and have been marketed under that name.  It has recently been established (Cooper, Reece and Furr, 1962) that the Bowen variety used in some of the early citrus breeding work in Florida was in reality Duncan.
      In flavor, Duncan has remained the standard of grapefruit excellence in Florida although seedless varieties have largely displaced it in the fresh fruit markets.  With the advent of processing, however, its flavor and better suitability for canning have renewed interest in this excellent variety and it constituted about 7 per cent of the grapefruit planted between 1956 and 1966.

Marsh (Marsh Seedless, White Marsh) (fig. 4-62)
      Fruit medium in size, oblate to spherical; areole ring indistinct or lacking; seeds few or none.  Color pale to light yellow at maturity.  Rind medium-thin, tough; surface very smooth and even.  Flesh buff-colored; tender, very juicy; flavor good though not so pronounced as in some seedy varieties.  Holds unusually well on the tree and ships and stores well.  The latest-maturing of all commercial varieties.
      Tree vigorous, spreading, large, and productive.  Because of high heat requirements, commercially restricted to very hot climates.
      According to Webber (1943), Marsh apparently originated as a chance seedling planted about 1860 on a farm near Lakeland, Florida.  Its commercial value as a seedless variety was not recognized until 1886, however, when it was brought to the attention of E. H. Tison of the Lakeland Nursery Company, who immediately arranged for its propagation and introduced it soon thereafter as a choice seedless variety.  A few years later it was given its present name by C. M. Marsh, who had acquired the Lakeland Nursery.  According to Mr. Tison, the owner of the farm on which the parent tree occurred insisted that it developed as a root sprout from an old seedling tree which produced seedy fruit.  While this is possible, it seems highly improbable.
      Primarily because of its comparative seedlessness, within a few years after its introduction Marsh became the variety most planted in Florida and virtually the only variety planted elsewhere.  It is still by far the leading variety and is worldwide in its distribution.
      Marsh is of unusual horticultural interest not only because it was the first seedless grapefruit variety discovered but also because the pigmented varieties currently of greatest commercial importance trace back to it.  Thus, Thompson (Pink Marsh) originated as a limb sport of Marsh and Redblush (Ruby) or Red Marsh occurred as a bud mutation of Thompson.  On the other hand, Marsh has also given rise to inferior bud variations, frequently characterized by a reversion to seediness.
      Other seedless varieties of more recent origin, virtually indistinguishable from Marsh, include Cecily of South Africa and Davis.
      Nucellar clonal budlines are currently of importance in Texas, Arizona and California, principal among which are Frost, CES (Citrus Experiment Station, Riverside, California), and USDA (U.S. Date and Citrus Station, Indio, California).  Reed, a seedling that originated in the dooryard of J. F. Reed of Taft, California, is one of the most recent selections to receive attention.

Triumph
      Fruit medium-small, oblate, globose, or ellipsoid; somewhat flattened at both ends; very seedy.  Color pale to light yellow.  Rind medium-thick with ver smooth surface.  Fish tender and very juicy; flavor lacking in bitterness and exceptionally good.  Early to midseason.
      Tree less vigorous than most grapefruits but productive.
      This was the first named grapefruit variety, having been offered to the public in 1884.  The parent tree, presumably a seedling, was situated in the grounds about the Orange Grove Hotel in Tampa, Florida.
      Being the first named variety, it was early and widely distributed though it did not achieve much commercial importance and has been little planted for many years.
      Its lack of bitterness and rich flavor are suggestive of the orange and some have thought that it might be a natural orangelo (orange-grapefruit hybrid).  In lack of bitterness it rather closely resembles Imperial of California origin and is somewhat like Mott (Aurantium), Leonardy, and Royal, all of Florida origin, though the latter is even more orange-like.  Indeed, these varieties appear to constitute a natural group of grapefruits in which the distinctive bitterness is lacking or they may be of hybrid origin.  With the exception of Triumph, currently employed primarily for home planting, none of them has attained commercial importance.
      The Jackson variety of South Africa is said to be a seedless budsport of Triumph.

Walters
      Walters is a midseason variety that produces medium-large, seedy fruits with relatively thin rinds and excellent and pronounced flavor.
      It originated as a seedling near Belleview, Marion County, Florida, and was introduced in 1887 by a Mr. Walters through a local nursery.
      Walters was never planted extensively but has special horticultural interest because it has given rise through bud mutation to two other varieties—Foster, the first pink-fleshed variety of record, and Cecily, a seedless South African variety similar to Marsh.

Wheeny
      See under pummelo hybrids.

White Marsh
      See under Marsh.

      Pigmented Grapefruit Varieties.—While pigmented pummelos have been known for centuries in the Orient and were early brought to the West Indies, it was not until 1907 that the first-recognized, pink-fleshed grapefruit, the seedy Foster variety, was found.  Shortly thereafter (1913), a seedless pink-fleshed limb sport of Marsh was discovered which in 1924 was propagated as the Thompson variety.  Only five years later a seedless red-fleshed fruit, Redblush (Ruby), was found as a limb sport of Thompson in the Lower Rio Grande Valley of Texas.
      Though of attractive appearance and excellent quality, because of its seediness the Foster variety never achieved commercial importance.  Thompson became available just as the Texas industry began its phenomenal development and was therefore planted extensively.  The favorable reception accorded it in the markets caused it to be planted somewhat extensively in Florida.  When Redblush became available in the markets, however, the deeper color of the flesh and the attractive pink blush on the rind, which is lacking in Thompson, made it an immediate favorite.  As a consequence, the Thompson variety rapidly lost favor and for years past Redblush has been the only pigmented variety widely planted.  Redblush is nowgrown extensively in Florida and Texas and to a limited but increasing extent in Arizona and California.
      Until processing methods are perfected to retain the natural color of the lycopene pigments, the utilization of the pigmented varieties will largely be restricted to fresh fruit outlets.  The conditions responsible for the development of the pink or red coloration are not well understood, but it is clear that they differ somewhat from those involved in coloration of the blood oranges.  That heat is a requisite is evident from the fact that coloration does not occur in regions of low total heat and is most intense in the hottest regions.  Also, no chilling requirement seems to be involved, for excellent coloration occurs in both Florida, Texas, and tropical regions.  Rootstock influence seems also to play an important role in coloration.¹⁸
      Although different pigments are involved and the climatic requisites for their development differ somewhat, the pink-fleshed grapefruits may be considered to correspond with the light blood oranges and the red-fleshed varieties with the deep blood orange group.
      Of particular interest in respect to the mode of origin of pigmented grapefruit varieties is a recent report (Cameron, Soost, and Olson, 1964) showing that nucellar seedling clones of the Thompson and Foster varieties do not exhibit the same degree of pigmentation as do the parent varieties.  Pigmentation is lost in the nucellar Thompson and increased in the nucellar Foster.  The degree of pigmentation remains unchanged, however, in the Redblush (Ruby) and Shambar varieties.  Convincing evidence is presented that chimeric constitution of the parent clones is the cause of this interesting behavior.  It is postulated that both clones are periclinical chimeras that carry a color factor in germ layers 1 and 11.  A somewhat similar situation is reported to exist in the true sweet lemon (Chapot, 1963d).
      The most important pigmented grapefruit varieties are described below:

Foster (Foster Pink)
      Fruit medium-large, oblate to spherical; basal furrows short, radiating; areolar ring indistinct; very seedy.  Primary color pale to light yellow, but under favorable conditions rind blushed with pink, extending into the albedo.  Rind medium-thick and surface smooth.  Primary flesh color chamois, but under favorable conditions pink; flesh texture tender and juicy; flavor good.  Medium-early in maturity.
      Tree vigorous, large, and productive.
      This variety originated as a limb sport in a tree of the Walters variety in an orchard near Ellenton, Florida, and was discovered in 1907 by R. B. Foster of nearby Manatee.  It was introduced in 1914 by the Royal Palms Nurseries, Oneco.
      Foster is of horticultural interest primarily because it is the first pigmented grapefruit variety of record in Florida.  As such, it attracted considerable attention and was planted to a limited extent both in Florida and Texas.  With the advent of the seedless pink-fleshed Thompson variety only ten years later, however, interest in Foster declined abruptly and it has not been planted for many years.
      Another reason for horticultural interest in this variety is the fact that in Texas it gave rise by bud mutation to the seedless pink-fleshed variety, Foster Seedless, which closely resembles Thompson but exhibits somewhat better flesh coloration.  Nucellar seedlings of Foster also possess more intense pigmentation than the parent clone.

Pink Marsh
      See under Thompson.

Redblush (Ruby, Red Marsh, Red Seedless) (fig. 4-63)
      Fruit similar to Thompson in all respects except for much deeper pigmentation in the flesh (but not in the juice), crimson blush on the rind, especially at points of contact between fruit; albedo pigmented.  Holds on tree as well as Marsh or Thompson but with some fading of flesh color.  Similar to Thompson in season of maturity.
      Tree indistinguishable from Thompson or Marsh.
      While the name Ruby has a slight time priority, Redblush seems preferable to avoid confusion with the much older Ruby orange variety.  Moreover, Redblush is more descriptive of this variety and is the name most used in the region of its origin.
      Ruby (Henninger Ruby Red) originated as a limb sport of Thompson that was found in 1929 by A. E. Henninger of McAllen, Texas, and patented by him in 1934.  So far as is known this was the first citrus variety to receive a patent (U.S. Plant Patent No. 53).
      Redblush (Webb Redblush) is said to have originated as a limb sport, also of Thompson, that was observed in 1931 by J. B. Webb of Donna, Texas, propagated soon thereafter, and introduced in 1934.
      Ruby and Redblush are so similar as to be indistinguishable and for all practical purposes they may be considered to be identical.  A number of similar bud mutations are known to have occurred subsequent to the two now generally propagated as Redblush or Ruby.  Thus, Waibel (1953) lists seven bud mutations which tests by the Texas Agricultural Experiment Station have shown do not differ significantly in appearance, season, or yield.  Ziegler and Wolfe (1961) state that several mutations have occurred in Florida that cannot be distinguished from Ruby.
      Nucellar clonal budlines are currently of great interest and are being planted commercially, in Texas, Arizona, and the Coachella Valley of California.  The oldest and most popular of these is CES Redblush No. 3, which was produced at the University of California Citrus Research Center, Riverside.
      Because of the attractive appearance provided by the pigmentation of the rind and its deeper flesh coloration, Redblush (Ruby) rapidly superseded Thompson and some years ago became by far the leading pigmented variety and one of the major grapefruit varieties.

Red Marsh
      See Redblush above.

Red Seedless
      See Redblush above.

Thompson (Pink Marsh)
      Fruit medium insize, oblate to spherical; areole indistinct or lacking; seeds few or none.  Pale to light yellow at maturity.  Rind medium-thin, tough, and surface very smooth.  Primary fleshcolor chamois to dark buff, but under favorable conditions light pink (but not in juice); albedo not pigmented; fleshtexture tender and juicy; flavor good, similar to Marsh.  Holds ontree unusually well, but with considerable fading of color; ships and stores well.Midseason in maturity, (earlier than Marsh).
      Tree vigorous, large, and productive.
      This variety originated as a limb sport in a Marsh tree in an orchard owned by W. B. Thompson at Oneco, Florida.  While discovered by S. A. Collins in 1913, it did not become available until 1924 when it was named and introduced by the Royal Palms Nurseries, also of Oneco.
      Because of its seedlessness, Thompson immediately attracted attention and was extensively planted in Texas and to some extent in Florida, quickly replacing the still new Foster variety.  In turn, it has long since been superseded by the more deeply pigmented Redblush variety, which also is more attractive because of the rind coloration it exhibits.
      Thompson remains of horticultural interest, however, because it was the first seedless pigmented variety to be discovered and within a few years gave rise by bud mutation to a number of more deeply pigmented clones.  Among these are Redblush, the variety that replaced it and has become by far the most important pigmented grapefruit variety, and the more recent Burgundy.  In addition, nucellar seedlings of Thompson do not exhibit the pigmentation of the parent clone.
      Several other pink-fleshed seedless limb sports of Marsh have been reported.  Shamel (1920) has described one which was found at Corona, California, and more recently Waibel (1953) has mentioned two which occurred in Texas.  All markedly resemble Thompson.

      Minor Grapefruit Varieties.—Both common and pigmented grapefruit varieties of minor importance are combined in the descriptions given below.

Burgundy (Burgundy Red)
      This variety produces a seedless, red-fleshed, late-ripening fruit that in Florida fails to develop external rind coloration.  It is said to be intermediate in size between Redblush (Ruby) and Thompson and somewhat less juicy than either.  The flesh color is appreciably deeper than Redblush and the color is retained much later.
      The parent tree was found about 1948 in an orchard of the Thompson variety near Ft. Pierce, Florida, that belonged to Hudson J. McReynolds of Orlando.  Since it occurred as an entire tree, the probability is that Burgundy originated as an undetected bud sport of Thompson that was unwittingly propagated by the Glen St. Mary Nurseries, who provided the trees for the McReynolds orchard.  Burgundy was introduced commercially in 1956 and has been planted to some extent.  According to F. E. Gardner of the U.S. Department of Agriculture, Orlando, who provided the facts given here, this variety received U.S. Plant Patent No. 1276 in 1954.  Like the parent variety, its nucellar seedlings are not true for pigmentation.

Cecily
      This South African variety is so similar to Marsh that the two are virtually indistinguishable.  It was found near Uitenhage, Cape Colony, in 1922, presumably as a limb sport, in a small planting of trees of the Walters variety that had been imported from Florida.  It was named by the owner, Sir Percy Fitzpatrick, in honor of his daughter Cecily.
      In South Africa, it is said to differ somewhat in growth habit from Marsh and the fruit is less oblate and of finer texture.  In California, however, these differences have not been noted.  It is grown to some extent in the region of its origin but is not replacing Marsh elsewhere.

CES Redblush
      This nucellar seedling of Redblush (Ruby) was derived at the University of California Citrus Research Center, Riverside, about 1945 and re]eased about ten years later.  That selection known as Number Three (No. 3) has been most used.

Clason
      Clason is a seedy, midseason, Arizonan variety that is indistinguishable from most of the named seedy Florida varieties.  Of unknown origin and probably a seedling, it was grown on a limited scale in the Salt River Valley for a decade or two but has not been planted in recent years.

Davis
      Davis is a seedless grapefruit variety in Florida so similar to Marsh that they are indistinguishable to the writer.  Traub and Robinson (1937, p. 778) state that there are minor differences, however, and report that Davis originated as a seedling, presumably of nucellar origin, that came "from a cross between a seedling type of grapefruit and a tangerine (in the attempt...to secure a tangelo)." Davis has not achieved commercial importance.

Foster Seedless
      This Texas variety is a seedless Foster with somewhat better rind coloration.  According to Waibel (1953), it was first noted in 1928 in the crop from a small planting of the Foster variety near Mission, Texas, made with trees brought in from Florida.  The limb sport was located in 1931, but the parent tree was inadvertently destroyed shortly thereafter.  Fortunately, however, it had been propagated and the clone was rediscovered by Joseph Hollerbach in 1932 in a young planting nearby.  Because of the availability of the more deeply-pigmented Redblush variety, however, Foster Seedless has not attained commercial importance.

Frost Marsh
      This variety is a nucellar seedling of Marsh that was derived by H. B. Frost of the University of California Citrus Research Center, Riverside, from seed planted in 1916.  It was introduced commercially in 1952.  Currently, it is the principal clonal selection of Marsh under propagation in California and South Africa.

Imperial
      This California variety produces a medium-small, very seedy fruit that lacks the typical grapefruit flavor and bitterness.  In this respect, it closely resembles the Triumph, Mott (Aurantium) and Royal varieties.  Of unknown origin, Imperial is presumed to be an introduction from Florida made about 1901 by the R. M. Teague Nurseries of San Dimas, California.  It never attained commercial importance and is included here primarily because of its use in the early citrus breeding program at the University of California Citrus Research Center, Riverside.

Jackson
      Jackson is a virtually seedless sport of Triumph with its characteristic tenderness of flesh, juiciness, and mild flavor.  It was found as a limb sport on the property of H. Jackson at Karino, eastern Transvaal, about 1945.  It was considered highly promising in South Africa and was planted to some extent, but has proven to be very susceptible to the widespread stem-pitting virus disease and hence is no longer much planted.

McCarty
      McCarty is an old seedy variety of high quality that was popular for some decades in the early history of the Florida industry.  A few orchards still exist.  Hume (1926) considered it to be somewhat distinctive in that the fruit is borne singly rather than in clusters.  Of unknown origin, it came to light at Rockledge, Florida, about 1886 and was named for C. T. McCarty of Eldred, who was a pioneer grapefruit grower.
      McCarty has not been generally propagated outside of Florida.

Royal
      This Florida variety has a relatively small, nearly round, orange-yellow, seedy fruit of sweet flavor that lacks the typical grapefruit bitterness and aroma and is suggestive of sweet orange.  While a distinctive variety, Royal has resemblances, notably in flavor and other respects, to such varieties as Triumph, Imperial, Mott and Leonardy, which suggests that they comprise a natural group and may possibly be grapefruit-orange hybrids (orangelos).
      Royal is said to have come originally from Cuba but was named and introduced in 1892 by the Royal Palm Nurseries of Oneco, Florida.  It was grown commercially for several decades but has not been planted for many years.

Shambar
      Shambar is a seedless, pink-fleshed fruit that resembles Redblush (Ruby) and has been reported to mature slightly earlier than Marsh or Redblush and to exhibit somewhat better color and flavor than the latter.
      It was discovered by Alec Barnes in 1936 as a limb sport of Marsh in an orchard of the Chace Brothers (later American Fruit Growers Company) at Corona, California.  It was first described by A. D. Shamel of the U.S. Department of Agriculture.  Shambar was introduced commercially in 1945, but has been little propagated.

Fruits Most Resembling the Grapefruit or Pummelo

      Tangelos.—While the tangelos (grapefruit-mandarin hybrids) of commercial importance more closely resemble mandarins than grapefruits, there are some of which the reverse is the case and hence they fall into this group.  The most important or interesting of these synthetic hybrids appear to be the following:

K-Early
      Fruit medium size, slightly subglobose; color yellowish-orange; seedy; rather acid.  Very early maturity.  Somewhat resembles the Orlando in appearance.
      K-Early is sometimes incorrectly called Sunrise, a name preempted by an older, very different, and little-known tangelo.  This variety is one of the first hybrids created by Webber and Swingle of the U.S. Department of Agriculture in Florida, and originally was not considered worthy of introduction.  Approximately two decades ago, it attracted the attention of John Kauffman, Sr. of the Grand Island Nurseries at Eustis, Florida, who was impressed by its very early coloring and maturity and propagated trees for commercial planting about 1945.  Although of comparatively poor quality, the high market returns it has received have stimulated both interest and planting in recent years.

Pearl
      Fruit medium-small, slightly oblate; color yellow; seedy.  Rind comparatively smooth, thin and tightly adherent; axis solid.  Flesh tender, juicy; flavor pleasantly sweet.  Medium-early in maturity and loses quality if left on tree past maturity.
      Tree vigorous, spreading, drooping, and somewhat alternate bearing.
      Pearl is similar in parentage to Allspice and was released in 1940 (Frost, 1940).  It is unattractive and too small in all but the hottest climates but may be suitable for home use.

Pina
      The Pina variety produces an early ripening, seedy, grapefruit-like fruit of medium-large size.  The tree is lacking in vigor.  Originated from the same Duncan grapefruit and Dancy tangerine cross that produced Minneola and Seminole, Pina has not achieved commercial importance.

Sampson (fig. 4-64)
      Fruit medium-sized, globose to slightly obovate; often somewhat necked; color orange-yellow; seedy.  Rind smooth, thin, relatively adherent; axis semi-hollow.  Flesh color dull orange; juicy, somewhat acid; flavor withdistinctive bitterish tang.  Late-midseason in maturity.  Seeds highly polyembryonic.
      Tree vigorous, spreading, large, and productive; leaves distinctive, cupped, and boat-like
      Sampson is a grapefruit and Dancy tangerine hybrid resulting from a cross made in 1897 by Swingle in Florida.  It was named and described by Webber and Swingle of the U.S. Department of Agriculture in 1904.  It has never attained commercial importance, except as a rootstock to a limited extent, but is still grown somewhat as an ornamental and an oddity.

Sunrise
      See under K-Early.

Sunshine
      Fruit large, grapefruit-like, slightly subglobose to somewhat oblong; color pale orange; seedy.  Flesh orange-colored; flavor acid.  Maturity very late.
      Tree vigorous and upright.
      Of the same parentage as Pina, Minneola, and Seminole, Sunshine has not achieved commercial importance, but is said to be promising as a rootstock in Florida.

Wekiwa (Pink tangelo)
      Fruit medium-small, spherical to obovate or pyriform; color pale yellow; seeds comparatively few.  Rind medium-thick, smooth, and fairly adherent; axis solid.  Flesh tender, juicy; flavor sweet and mildly acid, becoming unpleasant when overripe.  Under favorable conditions rind pink-blushed and flesh amber-pink.  Early in maturity.
      Tree lacking in vigor but productive; leaves small and rounded-oval.
      Wekiwa is a hybrid of grapefruit and Sampson tangelo and, therefore, is in reality a tangelolo.  It has not achieved commercial importance but is of interest as a novelty and because of its pink rind coloration.

      Orangelos.—If Chapot (1950a) is justified in his conclusion that certain so-called grapefruit varieties such as Imperial, Royal, and Triumph are in reality natural hybrids between the orange and grapefruit, they would obviously, fall in the orangelo category.  Since this view is not generally accepted and since such varieties differ so little, if at all, from the pure grapefruits, they have been included with the grapefruits.
      The fruit described below is considered by authorities familiar with it to be a natural orangelo.

Chironja
      Fruit large (grapefruit size), broadly obovoid to pyriform: low neck or broad somewhat furrowed collar; few-seeded, seeds strongly polyembryonic.  Rind medium-thin, smooth, moderately adherent but readily peelable; color bright yellow at maturity.  Segments about 10; axis medium-large and semi-open.  Flesh color yellowish-orange; tender, very juicy; flavor mild, lacking the bitterness of the grapefruit.  Midseason in maturity and fruit holds well on tree.
      Tree vigorous, large, and grapefruit-like; leaves broadly winged, somewhat cupped, and margins irregularly undulate.  Fruits usually borne singly rather than in clusters characteristic of grapefruit.
      Chironja recently came to notice in Puerto Rico and exhibits resemblances to both the orange and grapefruit, particularly to the latter.  The name represents a combination of Chi(na), the local term used for the sweet orange, and (to)ronja, the Spanish word for grapefruit.
      According to Moscoso (1958), from whom the characterization above is adapted, this fruit first came to his attention in 1956 as a wild seedling tree in the mountainous Angeles and Caguanas rural section of Utuado municipality.  Subsequently, however, other seedling trees were found in isolated areas of the coffee zone.  The parentage of Chironja is unknown, but it is thought to be a natural orangelo of local origin.  The fruit has attracted interest and limited quantities are available in the principal local market.

      Presumed Pummelo Hybrids.—Presumably largely because of its monoembryonic nature, natural hybrids of the pummelo abound in the Orient and exhibit a remarkable diversity of characters.  As might be expected, some of them have been found to possess desirable or acceptable qualities as fresh fruits and have come into commercial use.  The most important of these appear to be the Natsudaidai and Hassaku in Japan and the so-called Poorman orange, Smooth Seville, and Wheeny grapefruit in Australia and New Zealand.  Of minor importance is the so-called Tiniura tangelo of New Zealand.

Hassaku (Hassaku Mikan or Zabon) [C. hassaku Hort. ex Tanaka] (fig. 4-65)
      Fruit medium-large (9-10 cm in diameter), slightly oblate; both ends somewhat depressed; seedy and monoembryonic.  Rind color orange-yellow; medium-thick; surface somewhat coarsely pebbled; moderately adherent.  Segments numerous; axis large and semi-hollow at maturity.  Flesh color light yellow; somewhat coarse-grained; lacking in juice; flavor good.  Early midseason in maturity and stores only moderately well.
      Tree vigorous, upright, virtually thornless; leaves large and pummelo-like, but petiole wings narrower, approaching sweet orange.
      Hassaku is said to have originated as a chance seedling in Hiroshma Prefecture, Japan.  It was noted and named in 1860, but was not propagated and planted commercially until about 1925.  In 1964, Japanese planting was reportedly in excess of 2,500 acres, mostly in the prefecture of its origin.  During the 1960's, however, it has been planted increasingly elsewhere.
      Its characteristic strongly suggest pummelo-mandarin parentage with pummelo predominant.

Kawano
      See under Natsudaidai below.

Natsudaidai [C. natsudaidai Hayata](fig. 4-66)
      Fruit medium to medium-large (grapefruit size), broadly obovate to oblate; sometimes with very short collared neck and apex slightly depressed; moderately seedy.  Color yellowish-orange.  Rind medium-thick; surface coarsely pebbled slightly rough; moderately seedy.  Color yellowish orange.  Rind medium-thick; surface coarsely pebbled, sometimes slightly rough; moderately adherent (peels readily).  Segments fairly numerous (12); axis large and semi-hollowat maturity.  Flavor acid and refreshing.  Late in maturity (summer-maturing in most climates).  Holds well on the tree and improves in storage.
      Tree vigorous and upright-spreading with few stout thorns; leaves large, dark green, and mandarin-like.
      The Natsudaidai tree is reported to be less cold resistant than the satsuma mandarin in Japan.  Its behavior there and in the coastal regions of southern California indicates a heat requirement for fruit maturity somewhat less than that of the grapefruit and comparable with the so-called Poorman orange and Wheeny grapefruit of New Zealand and Australia, both of which attain acceptable quality in climates too cool for satisfactory maturity of the grapefruit.  Nevertheless, even at full maturity the Natsudaidai remains too acid for some palates.
      The original seedling tree of this fruit is said to have been found in a garden in Yamaguchi Prefecture, Japan, toward the end of the 17th century and is reported still alive.  The value of its late-ripening characteristic was not appreciated until approximately a century later and is reflected in the names most commonly used for it (natsu means summer).  Other names include natsumikan, natsukan, daidai mikan, and Japanese summer grapefruit or orange.
      Natsudaidai is extensively grown in the Japanese coastal regions of mildest winters and is currently second in importance only to the satsumamandarin.  The Statistical Yearbook of the Japanese Ministry of Agriculture and Forestry reports that the 1961 acreage was approximately 28,000 with a productionof about 173,000 tons, accounting for some 15 per cent of the total production of Japanese citrus fruits (see chap. 2, table 2-1, pp. 42-43 [text version, Revised Ed.]).
      The Natsudaidai exhibits characters of the pummelo or sour orange and the mandarin.  In the writer's opinion, the evidence supports the conclusion of Tanaka (1954, p. 91) that the pummelo is involved in its parentage.
      Numerous unnamed clones and selections are grown, some of which exhibit minor differences, but only two derivative varieties—Kawano and Tajima—have been named and propagated commercially.  The former differs appreciably from the common Natsudaidai only in the fact that the fruit is less acid (and hence sweeter), matures much earlier, and loses quality if held on the tree after maturity.  It is said to have originated as a limb sport in an orchard in Oita Prefecture about 1905 and was named and registered in 1950.  It is currently recommended for planting in several districts.  Tajima is a new and very juicy, late-ripening, high acid variety of much less importance, but considered to be promising.

Morrison (Morrison Seedless)
      See under Poorman below.

New Zealand
      See under Poorman below.

Poorman (Poorman Orange, New Zealand Grapefruit) (fig. 4-67)
      Fruit medium-large, oblate to broadly obovate to nearly globose; seeds numerous but monoembryonic. Color pale orange-yellow at maturity (deeper than any of the grapefruits).  Rind medium-thick with fairly rugose surface (somewhat more so than Wheeny).  Flesh color yellowish-orange; coarse-textured, juicy; flavor pleasantly subacid with trace of bitterness.  Very early in maturity (as compared to the grapefruits).  Much earlier than Wheeny, but holds on tree exceptionally well without loss in quality.
      Tree vigorous, large, and prolific; leaves dark green, with petioles suggestive of mandarin or bitter orange rather than grapefruit.  Most Australian selections and some in New Zealand exhibit a peculiar and distinctive bark condition, which in California appears to be associated with dwarfing.  Surface of trunk and main limbs markedly rough and grayish-black in color; dull-black streaks on smaller branches and twigs.
      Although obviously not an orange, the names Poorman Orange or Poorman are employed for this fruit in Australia, where it first came to notice.  Since it most resembles the grapefruit in both appearance and use and is the citrus fruit most extensively grown in New Zealand, the preferable name for this interesting and distinctive fruit would appear to be New Zealand Grapefruit.
      A total heat requirement considerably lower than for any of the true grapefruits is indicated by the earlier maturity of Poorman and the fact that it ripens in New Zealand and parts of southern California where there is insufficient heat for any of the present grapefruit varieties.
      That Poorman originated in the Orient is suggested by Bowman's statement (1956) that it was brought to Australia (presumably the fruit) from Shanghai by a Captain Simpson.  The earliest description of record, given in a New South Wales nursery catalogue of 1820, indicates that the original introduction might have been a shaddock (pummelo); hence, the possibility exists that Poorman is of Australian origin.  Since the seeds are monoembryonic, early references to the existence of clones varying appreciably in fruit characteristics, and to the possibility of hybrid origin, are understandable.  According to Bowman (1956), this fruit was taken to New Zealand by Sir George Grey, who established his home on Kawau Island about 1855.  About 1861, Grey provided propagation materials to John Morrison of Warkworth, for whom the clone currently most widely grown in New Zealand was named.
      Although generally distributed and commonly available in the markets, Poorman has not achieved much commercial importance in Australia, presumably because of the availability of grapefruits.  In New Zealand, however, where grapefruit does not succeed, under the name of New Zealand Grapefruit it has become the principal citrus fruit grown and currently comprises about 85 per cent of the so-called grapefruit acreage, the balance consisting of the low-heat-requiring Wheeny variety.  The 1962-63 crop of 167,000 bushels (40-1b) is said to have accounted for 55 per cent of the total citrus production in New Zealand.  While principally used as a breakfast fruit, the juice is also canned and the immature fruits are extensively used for marmalade purposes.  Morrison (Morrison Seedless) is considered to be the best clone.  It is seedless, however, only in the absence of cross-pollination.
      Almost certainly Poorman is a pummelo hybrid and probably a natural tangelo.  The fruit has some resemblance to the Attani of India and the Natsudaidai and Asahikun of Japan.

Smooth Seville (Smooth Flat Seville) (fig. 4-68)
      Fruit similar to Poorman in size, form, and flavor, but rind surface very smooth; both rind and flesh color reddish-orange; seeds exhibit low polyembryony (usually one, occasionally two embryos).
      Tree and foliage similar to Poorman but tree commonly more vigorous and larger.  Younger branches also exhibit dark bark streaks characteristic of Poorman.  Distinctive rough bark condition on trunk and main branches which affects some Poorman selections not observed so far on Smooth Seville trees.¹⁹
      This is an old Australian fruit that is thought to have originated as a seedling of unknown parentage and has generally been regarded as a sweet orange and grapefruit hybrid.  Its age and numerous resemblances to Poorman, however, suggest that it may be of similar origin and possibly a sister seedling.
      Like Poorman, Smooth Seville has a lower heat requirement for maturity than the grapefruit and hence ripens earlier and serves as a satisfactory substitute.

Tajima
      See under Natsudaidai.

Wheeny (Wheeny Grapefruit) (fig. 4-69)
      Fruit large, oblate or very broadly obovate to globose; both ends depressed, with small radially-furrowed basal cavity and broad, shallow apical basin; moderately seedy but monoembryonic.  Color pale to light yellow.  Rind medium-thin with moderately rugose surface (not smooth as are most grapefruits).  Flesh straw-colored; coarse textured but very juicy; flavor good but acid (virtually indistinguishable from some grapefruits).  Medium-early in maturity (as compared to the true grapefruits).
      Tree vigorous, spreading, large, and productive with tendency to alternation in bearing.  Leaves longer and more pointed than most grapefruits and somewhat bullate (puckered), with comparatively narrow petiole wings.
      A lower total heat requirement than for grapefruit is indicated by the fact that in both New Zealand and coastal southern California Wheeny ripens satisfactorily in climates too cool for any of the true grapefruits.  Under conditions favorable to grapefruit, it matures earlier and develops quality equal or superior to many grapefruit varieties.
      This variety originated as a chance seedling at Wheeny Creek near Kurrajong, New South Wales, Australia, and was named by R. J. Benton, government citrus specialist.  It is of principal importance in New Zealand, however, where it was introduced about 1935 and now constitutes about 15 per cent of the so-called grapefruit acreage, the balance being provided by the New Zealand Grapefruit or Poorman Orange.  Under heat-deficient climatic conditions in Australia and New Zealand, Wheeny is a summer-maturing variety.
      While the fruit is grapefruit-like in most respects, the monoembryonic nature of the seeds and some of the other characters suggest that it is probably a pummelo hybrid.

      Pummelo-like Fruits of Minor Importance.—Of limited commercial importance in Japan are several other pummelo-like fruits either known or thought to have originated as chance seedlings.  Among them are the following:
      Banôkan [C. grandis var. banokan Tan.]—A medium-large, yellow, oblate to subglobose, thick-rinded, juicy, subacid fruit of good flavor and late maturity.  Both tree and fruit are very much like pummelo.
      Hyûganatsu [C. tamurana Tan.]—A medium-sized, light yellow, globose to oblong, juicy, sweet-flavored, moderately seedy, late-ripening fruit which requires cross-pollination.
      Kinkôji [C. obovoidea Takahashi]—A medium-small, yellowish-orange, subglobose to obovoid, pleasantly flavored fruit of medium-late maturity and with highly polyembryonic seeds.  An old fruit of unknown origin, but apparently a pummelo-mandarin hybrid.
      Kinukawa [C. glaberrima Tan.]—A medium-sized, bright yellow, oblate to globose, juicy, sweet-flavored pummelo-like fruit of midseason maturity.  Monoembryonic.
      Not commercially important but of interest in the category of pummelo-like fruits are the Asahikan (C. asahikan Tan.) of Japan and the Attani (C. rugulosa Tan.) of India.

COMMON ACID MEMBERS—CITRON, LEMON, AND LIME
      That the citrons, lemons, and limes constitute a natural group is indicated by the distinctive characters they possess in common and their numerous resemblances.  Indeed, the earlier botanists, almost without exception, placed them in the same species and considered the lemon and lime to be botanical varieties.  The most distinctive fruit characters of the acid members are high acidity (all three have sweet or acidless forms, however) and an oval to elliptical shape with areolar mammilla or nipple (sometimes suppressed, however).  All are more or less everflowering, everbearing, and highly sensitive to cold.
      The differences the acid members exhibit are so numerous and striking, however, that they have long since been separated into species.  Indeed, the limes are generally considered to comprise several species.
      In comparison, therefore, this natural group exhibits a much wider range of variation than any other citrus group.  Thus, the citron is among the largest and, because of its very thick and dense rind, is the heaviest of all citrus fruits, whereas the Indian sour lime is among the smallest and thinnest-skinned.  On the other hand, the citron plant is a thick-stemmed shrub or small tree with large elliptical, nearly round-pointed leaves, while the Indian sour lime is a good-sized, fine-stemmed tree with very small lanceolate, sharp-pointed leaves.  The lemons and some of the limes are intermediate between these extremes.  Finally, the citrons are monoembryonic, the lemons only slightly polyembryonic, and some of the limes highly polyembryonic.
      In northeastern India and adjoining portions of their general area of origin, natural hybrids with characters of the citron or lemon are common and there can be little doubt that they have contributed to the list of distinctive and little-known Indian fruits (Hodgson, Singh, and Singh, 1963).  Among those fruits in which citron characters are discernible are the amilbed and sadaphal and among those in which lemon characters are evident are the galgal and jambhiri or jamberi.  Citron-like fruits of the Western World include the lumias of the Mediterranean and the so-called Ponderosa lemon and Cuban shaddock.
      Lemon varieties in which citron characters are discernible have long been known and include the pat nebu, Nepali Oblong or Assam and others of India, Interdonato of Italy, and San Jeronimo of Portugal.  Lemon-lime hybrids are represented by the Perrine lemonime of Florida.

Citron (Citrus medica L.)

      The citron is the cedro or cedrone of Italy, cidra or poncil of Spain, cedrat of France, and bushukon of Japan.  Unfortunately,the fact that the modern French word for lemon is citron has led to considerable confusion and ambiguity in the literature.
      That this fruit probably had its origin in northeastern India and adjoining areas is suggested from the facts that it is found growing wild in parts of that region and that natural hybrids in which its characters appear are abundant there.  It seems early to have spread to Media and Persia where it became known to the Greeks and somewhat later to the Romans, who considered it to be indigenous there and called it the Persian or Median apple (from which its species designation was derived).  It must have reached the Holy Land not long thereafter.  Most Jewish scholars agree that the hadar or "goodly fruit" of the Bible (Lev. 23:40) is the citron, which, if true, would date its earliest reference in the Holy Land to the thirteenth century B.C. (see chap 1, this work).
      There can be little doubt that the citron was the first citrus fruit brought under cultivation and the first to reach the Mediterranean and to become known to Europeans (Tolkowsky, 1938).  Evidence indicates that it was introduced into Italy in the first century (see chap. 1, this work).  Like most of the other citrus fruits, it was taken to the West Indies and to Brazil soon after the discovery of the New World.  It was early brought to California from Mexico by the Spanish Mission fathers (Butterfield, 1963).
      The citron is highly distinctive in both plant and fruit characteristics.  The plant is a comparatively short-lived, thick-stemmed, straggly growing, thorny shrub or small tree with light gray bark and relatively soft wood.  It is highly sensitive to frost injury and recovers slowly, if at all.  The leaves are large, oval to oblong, with rumpled blades and serrate margins, and short, wingless petioles not visibly articulated with the blades.  The flowers are large, purple-tinged or not, with a variable and often high proportion male (by pistil abortion), and are produced throughout the year.  The fruits are large to very large and of variable form, but usually oblong and blunt-pointed, with pronounced mammilla and often with persistent style.  The yellow rind is very thick, fleshy and tightly adherent (cannot be peeled by hand because the carpellary membranes are separated by albedo tissue, fig. 4-70).  The rind has a smooth but often bumpy surface.  The rind oil is pleasantly aromatic.  The flesh is small in amount, firm, and lacking in juice.  The juice is either acid or sweet.  The seeds are numerous, monoembryonic, and distinctive in form, with a pronounced beak and white cotyledons.
      Since the fruit is virtually indelible and neither tree nor fruit is particularly ornamental, the question is often raised as to why the ancient Greeks and Romans held the citron in such high esteem as indicated in their early literature.  It would appear that the reasons were that the fragrance of the fruit is delicate, penetrating, and lasting, and it was the only citrus fruit with which the Romans were acquainted.  For many centuries its main use seems to have been as a perfumant and moth repellant.
      Much later, when sugar became available, there developed the utilization on which the present commercial industry is based—candying of the peel.  In candying, the fruits are cut into halves, and the pulp is removed.  The halves are placed in brine (commonly sea water) for a month or thereabouts, during which a fermentation occurs.  The halves are then removed, washed, and held in a somewhat stronger brine until used for candying.  The fruit is commonly exported in brine to buyers in the markets where it is to be candied, which are principally in France, Great Britain, and the United States.  The candied peel is an essential constituent in certain cakes and confections.
      Much the oldest use of the citron, although obviously highly limited, is that previously mentioned, namely, in connection with the orthodox observance of the Jewish Feast of Tabernacles (Succoth).  The Etrog or Ethrog required in the ceremonies is a small but relatively mature citron which, according to Chapot (1950b), must be fresh (not preserved), clean, without defects such as wounds or scars, and symmetrical with a persistent style.  The Etrog must also come from a tree which has not been grafted (cutting or seeding).  While there is an Etrog variety, any citron fruit which meets these requirements is said to be acceptable.  Such fruits are often expensive.
      Because of its sensitivity to frost and heat injury, the commercial culture of citron is restricted to regions where the winters are mild and summer temperatures are not excessively high.  Because of the premium received for unblemished fruits, it is especially subject to loss of quality from wind damage.  The Mediterranean areas where these requirements are best met consist primarily of the southern portion of the Italian and Grecian peninsulas and nearby islands.  Thus, the principal citron-producing countries are France (Corsica), Italy (Calabria, Sicily, and Sardinia), and Greece (mainly Crete and other islands), although small quantities are produced elsewhere.  Corsica is said to account for about a third of the world supply, and total plantings in Italy are currently estimated at about 3,000 acres.
      The citron has been successfully grown and processed in southern California, but its culture has not persisted because of inability to withstand competition from the Mediterranean.
      Citron culture as practiced in the Mediterranean area exhibits several features of special interest to horticulturists: (1) it is largely located on relatively steep, terraced slopes; (2) the trees are mainly propagated from cuttings; and (3) protection against frost and prevention against wind injury are commonly provided by means of a pole framework on which straw matting is fastened during the winter and to which the branches of the trees are tied to prevent breakage and injury to the fruit from swaying under wind action.
      While the citron exhibits a wide range in fruit size and form, including the famous fingered citron (fig. 4-71) of the Orient, all varieties appear to fall into two natural groups—the acid or sour citrons and the acidless sweet citrons.  The former are distinguished by flowers that are purple in the bud and purple-tinged when open, pink-colored new shoot growth, acid pulp, and seeds with a dark-colored inner seed coat and chalazal spot.  In contrast, neither flowers nor shoot growth of the sweet citrons exhibit pink coloration, the pulp is lacking in acid and hence sweet, and the inner seed coat is colorless and the chalazal spot light yellow.

      Major Acid Citron Varieties.—The Diamonte and the Etrog are the two acid citron varieties of greatest significance.  They are described below.

Atrog
      See under Etrog.

Cedro Liscio
      See under Diamante below.

Diamante (Cedro Liscio) (figs. 4-7 [sic, i.e., 4-70] and 4-72)
      Fruitlarge, long-oval to ellipsoid; basal cavity furrowed and surrounded by low collar; apex broadly nippled; and seedy.  Color lemon-yellow at maturity.  Rind very thick and fleshy; surface smooth and sometimes indistinctly lobed or ribbed.  Flesh crisp; lacking in juice, but acid, like lemon.
      Tree small, open and spreading, medium-thorny with some large, stout spines; buds, flowers, and new growth purple-tinted.
      Presumably of local though unknown origin, Diamante is the principal variety of Italy and according to Casella (1928) is considered to be the best.  It was introduced into the United States in 1898.  Italian and Sicilian are California introductions that are similar to Diamante.

Ethrog
      See under Etrog below.

Etrog (Atrog, Ethrog)
      Fruit medium-small, ellipsoid to fusiform or lemon-shaped; commonly with fairly distinct neck and prominent apical nipple; frequently with persistent style; seedy.  Lemon-yellow at maturity.  Rind thick and fleshy; surface slightly ribbed, somewhat rough, and bumpy.  Flesh crisp and firm; low in juice content; flavor acid.
      Tree smaller and less vigorous and productive than most citrons; leaves more round-pointed and downward cupped.  Flower buds, flowers, and new growth purple-tinted.
      Under the name of Etrog and its synonyms, at least two introductions from Palestine have been received in the United States which correspond with the above general characterization, although there are minor differences.  They are evidently selections made for ritual purposes, though, as previously mentioned, any citron fruit that meets the specified requirements is acceptable.  In neither has the per cent of persistent styles been above average.
      Jericho Ethrog is said to be currently the most widely planted citron in Israel and is characterized by relatively small fruit size, oval shape, and deeply corrugated rind surface.  It is reported to be of local origin and to reproduce true to type from seed even though monoembryonic, in which respect it is similar to several of the United States introductions.
      From the materials available in California, there appears to be little justification for Swingle's classification of this fruit as the botanical variety ethrog (see chap. 3, this work).

Italian
      See underDiamante.

Jericho
      See under Etrog.

Sicilian
      See under Diamante.

      Minor Acid Citron Varieties.—While there are a number of varieties of the acid citron group, only two of these were considered sufficiently important in judging the literature to warrant specific description in the previous subsection.  Some of the better known minor varieties are briefly discussed below.
      Poncire is doubtless the oldest known citron variety for it was described by Risso and Poiteau (1818-1822).  The word poncire is from an old dialect of southern France (Provence) and means Syrian apple.  Saigon is reported in Algeria and Morocco and to judge from the name must have been introduced from Indo-China.  Earle, described and named by Webber (1943), closely resembles Diamante.  It was introduced from Cuba in 1914 and named for the owner of the orchard from which it was selected.  China (Chinese or China lemon) is a small-leafed citron, the fruits of which are also small, lemon-shaped, roughly corrugated, and worthless.  Supposedly from China, it was employed as a rootstock in the early history of the citrus industry in California but was soon found unsuitable and abandoned.
      A most unusual and interesting citron is the fingered or Buddha's Hand citron (fig. 4-71) of the Orient (bushukan of Japan), where it has been prized for centuries, especially in Indo-China, China and Japan.  As the name indicates, the fruit is apically split into a number of fingerlike sections, somewhat resembling a human hand.  There appear to be two clones—one in which all the fruits are deeply fingered and lacking in flesh development and seeds, the other in which only part of the fruits are fingered and the rest are corrugated, lacking in flesh, and contain seeds hanging free in the locules.  Both are typical acid citrons in all other respects and would seem to constitute clonal varieties rather than the botanical variety sarcodactylis as they are classified by Swingle (see chap. 3, this work).

      Sweet Citron Varieties.—The only widely-grown sweet citron variety is the Corsican, which is described below.  The literature does not disclose other sweet-fruited varieties of general distribution.  That there are some varieties of local importance is indicated by Chapot (1950b and 1962a), who described two of Moroccan origin: Assads and M'Guergueb.  The California introduction Dulcia, the fruit of which is smaller than the Corsican and almost flat, is another variety in this local category.

Citron of Commerce
      See under Corsican below.

Corsican (fig. 4-70 and 4-73)
      Fruit large, ellipsoid to very slightly obovate; basal area slightly depressed and radially furrowed; apical nipple suppressed or indistinct (less prominent than in Diamante); seedy.  Color lemon-yellow.  Rind very thick and fleshy; surface rather rough, bumpy, and commonly somewhat ribbed.  Flesh crisp and solid; lacking in juice; flavor sweet (without acid).
      Tree small, open and spreading; medium-thorny with some large, stout spines (vary much like Diamante); buds, flowers and new growth not purpie-tinted.
      This variety is said to be the best and most important citron in Corsica and presumably originated there, although its history is unknown.  It was introduced into the United States about 1891 and distributed under the name Corsican.  Citron of Commerce in California is indistinguishable.

      Fruits Resembling the Citron.—There are numerous fruits in which citron characters are strongly pronounced.  The lumias of the Mediterranean basin are natural hybrids in which acid citron or lemon and pummelo characters are evident.  According to Chapot (1950a), they are characterized by fruits of large size, commonly somewhat pyriform, with highly acid flesh of greenish color, large purple-tinged flowers, and young shoot growth both pubescent and purple-tinted.  Chapot states that the principal clonal varieties are Poire du Commandeur, Citron de Borneo (Chapot, 1964d), and Pomme d'Adam.  They are of ancient and unknown origin, presumably Italian, and are grown only as curiosities or ornamentals.
      The giant-fruited Sui Khar citron of Punjab State (Hodgson, Singh and Singh, 1963), the Kabbad citron of Damascus (Chapot, 1963f), and the yemmakaipuli of Coorg (India) also appear to fall in this group.
      Only two of the fruits resembling the citron, however, are of sufficient importance or interest, to warrant specific descriptions.  These are the so-called Cuban shaddock and the Ponderosa lemon.

American Wonder
      See under Ponderosa.

Cuban (Cuban Shaddock or Lemon)
      Fruit large to very large, globose to obovate; color [sic] depressed and deeply furrowed at base; apex rounded or depressed, but sometimes with low and indistinct nipple; seeds numerous.  Color lemon-yellow at maturity.  Rind thick and spongy; surface rough, bumpy, and commonly somewhat furrowed.  Flesh color yellowish-green; coarse-textured, juicy; flavor acid.
      Tree vigorous, upright, spreading, large, thorny, and productive; foliage dense.  Leaves large, oblong-elliptic, and blunt-pointed.  Flowers and new growth not purple-tinted.  Tree sensitive to cold.
      While the Cuban shaddock somewhat resembles the pummelo in appearance, most of the characters are those of the citron or lemon.  As the name suggests, this fruit was introduced from Cuba, where it is referred to as a shaddock and for a time was recommended as a rootstock.  It remains only a horticultural curiosity.

Ponderosa (Ponderosa Lemon, Wonder, American Wonder) (fig. 4-74)
      Fruit medium-large, obovoid; collar radially ribbed or furrowed or short neck and low broad apical nipple; color lemon-yellow; seedy and monoembyonic.  Rind medium-thick and fleshy; surface smooth but slightly bumpy and indistinctly ribbed.  Flesh color pale green; juicy; flavor acid.  Fruits mature throughout year.
      Tree small, round-topped, and productive; branches medium-thick and theory; leaves large elliptical to oblong and citron-like.  Flowers and new growth purple-tinged.  Everflowering.  Tree sensitive to cold.
      Both fruit and plant are clearly citron in most respects, and there can be little doubt that Ponderosa is a hybrid between citron and lemon.  According to Webber (1943), this variety originated about 1887 as a chance seedling (presumably of lemon) grown by George Bowman of Hagerstown, Maryland, and was named and introduced to the nursery trade in 1900.  If this account is accurate, the fruitfrom which the seed was obtained must have been of Italian origin.
      Ponderosa is of importance primarily as an oddity and ornamental, although the fruit can be used as a lemon substitute.  It is used somewhat as a tubbed plant in patios but most commonly as a dooryard ornamental in California and Florida.

Wonder
      See under Ponderosa above.

Lemon (Citrus limon [L.] Burm. f)

      The lemon is the limone of Italy, the limon of Spain, and the citron of France.  The fact that the French name is the same as the English name for a quite different, closely related fruit has led to both confusion and ambiguity in the literature.
      The lemon must have originated in the eastern Himalayan region of India and adjoining areas, also the home of the citron, for natural hybrids with citron and lemon characters are abundant there.  Indeed, most of the lemon-like fruits of India exhibit citron characters to some degree.  It is an interesting fact, however, that lemons of the common Mediterranean type have not been found growing wild in any part of that region or elsewhere.  For reasons that are not clear, possibly its more recent origin, the lemon as we know it seems to have spread to the Mediterranean and reached Europe much later than the citron (see chap 1, p. 6).
      From archeological evidence, Tolkowsky (1938) has concluded that the lemon reached Italy by the end of the second century and was among the fruits taken by the Arabs to Spain prior to 1150 A.D.(see chap. 1, this work).  It is clear that the Arabs took the lemon to the Mediterranean and across North Africa to Spain, for Arab writers of the twelfth century mention itas among the citrus fruits grown there at that time.  It is also certain that tae Crusaders took it from Palestine to southern Europe, Italy in particular, not long thereafter.  It is known that the lemon was among the fruits taken to the New World by Columbus on his second voyage in 1493.
      The lemon tree is vigorous, upright-spreading, and open in growth habit.  It attains large size under favorable conditions if not controlled by pruning.  Seedlings and most varieties are comparatively thorny, with relatively short and slender spines.  The light-green leaves are lanceolate in form with short, wing-margined petioles.  The flowers, which occur in clusters produced throughout the year, are large and purple-tinged in the bud and on the lower surface of the petals.  Many are sterile because of pistil abortion, which varies greatly from bloom to bloom and season to season.  The new shoot growth is purple-tinted.
      The fruit characteristics are so well known as scarcely to require description.  Mention should be made, however, of the distinctive form and apical mammilla or nipple, the tight adherence of the highly fragrant rind, and the high acidity of the pale, straw-colored flesh.
      Although more resistant than the citron and limes to cold and heat, the lemon is much more sensitive than the other citrus fruits of major importance, and hence its commercial culture is restricted to subtropical regions of mild winter temperatures.  Relatively equable growing-season temperatures are advantageous in that they seem to emphasize the ever-flowering tendency and are favorable for fruit-setting.  As a consequence, the seasonal distribution of the crop is such as to provide the maximum output during late spring and summer, when prices are normally high and there is a minimum storage requirement.  Thus, in regions characterized by mild winters and cool equable summers, marketable fruit is available throughout the year with a minimum requirement for frost-protection and fruit storage, both of which are expensive.  These facts serve to explain why, with minor exceptions, the principal commercial lemon-producing areas of the world are in coastal locations of southern California, Sicily, Greece, and Spain.  By contrast, the picking season generally ininterior districts is shorter and a much higher percentage of the crops come during the fall and winter, when prices are usually lower and longer storage is required for the summer markets.  On the other hand, the fall and winter fruit ships and stores well and is higher in acid content.
      Lemons are little grown in semitropical and tropical regions.  In such regions, the sour lime is better adapted to both heat and humidity and is generally preferred.  In addition, lemon size is undesirably large in relation to market demand, rind diseases are prevalent, and storage is difficult and expensive.  If economically justifiable, however, it may be horticulturally practicable to produce lemons for processing purposes in such climates.
      The fact that the lemon is grown primarily for the acid it contains, a constituent which is at its maximum prior to the attainment of horticultural maturity, affords possibilities in fruit-handling which have found numerous and important applications in practice.  Indeed, development and utilization of such handling methods are largely responsible for the success of the California industry in supplying the needs of North America and invading the highly competitive markets of Europe.  Specialized handling methods perfected in California include:
      1. Picking according to fruit size rather than maturity.
      2. Maturity grading by means of separation according to color.
      3. Curing of fruit prior to packing.
      4. Regulated and controlled storage.
      At each picking, all fruit which will not pass through a metal ring of predetermined diameter is harvested irrespective of maturity.  By far the greater part of the crop is therefore immature and of maximum acid content and storage life when picked.
      Accurate separation of fruit into color grades is perhaps the most important single operation in the packing house, for it determines the curing possibilities and storage life of the fruit.  Four color grades are usually made—from "tree ripe" (yellow) with a storage life of a few weeks only (generally sent direct to the processing plant), through "silver" (yellowish-green) and "light green" to "dark green," with a commercial storage life of six months or more.
      Since freshly picked lemons are mostly immature, they are firm and turgid and the rinds are thick and fleshy.  They are therefore highly sensitive to injury, resulting in rind spotting or decay.  Indeed, lemons should not be picked in early morning when they are at a maximum turgidity or when there is water on the fruit, for the escape of rind oil during handling may cause rind injury followed by spotting.  During storage, however, the rind loses moisture, thins down, and becomes tough, leathery, and markedly resistant to injuries from handling operations.  Such changes, usually associated with the development or intensification of the yellow color, constitute the "curing" process, which greatly improves the appearance of the fruit and contributes to successful long-distance shipment.
      Curing proceeds slowly at the usual storage temperatures of 55º F to 60º F and relative humidities of 75 to 85 per cent, but it is normally completed long before the fruit is packed and shipped.  Curing can be markedly accelerated, however, by raising the temperature and adding ethylene gas in dilute concentration to the storage atmosphere, thus converting highly immature, dark green fruit to an attractive, salable product in a matter of weeks.
      The use of regulated or controlled storage and the availability of means for accelerating curing—all prior to packing—provide the flexibility in packinghouse operations necessary for successful adjustment between the highly variable and uncontrollable receipt of fruit from the orchards and the even more variable and uncontrollable market demand.
      California's highly important handling practices, supplemented by the more recent development of treatment of the fruit with 2,4-D to reduce the tendency to abscission of the "buttons" (fruit calyces) during curing and the use of gibberellin sprays to retard the maturity of the fruit, are almost unique in the lemon industry.
      The most unusual orchard management practice in lemon culture is the forcing or verdelli (summer lemons) treatment which has been employed in Sicily for many decades.  Its purpose is to materially accentuate the late summer bloom (August-September) and thus increase the crop, which matures the following summer when prices are normally high.  This is accomplished by withholding irrigation during the summer (June-July) until the trees have wilted, followed by an application of nitrogenous fertilizer and renewal of irrigation.  If the trees have been sufficiently stressed, the result is a greatly increased late summer bloom and a summer or verdelli crop the following year and a reduced winter crop.  A deeper than average cultivation is sometimes employed to supplement the suspension of irrigation.  Unless carefully controlled, this practice is harmful.  For this reason, it is usually employed on a rotational basis, every other year or every third year.  A somewhat similar treatment is used for the production of summer sour limes in the Faiyûm oasis of Egypt and for the control of the blossoming of oranges and mandarins in central and southern India.
      The lemon is still used primarily as a fresh fruit, although in the United States the trend of shipment to the markets has been downward for some years past.  Likewise, the per capita consumption of lemons in all forms has slowly declined.  The principal fresh fruit uses of the lemon are for the making of lemonade, as a garnish for fish and meats, and for a wide variety of culinary preparations—pies, cakes, ices, and the like—and as flavoring for candies, jellies, jams, and marmalades.  Lemon juice is the principal product, of course, and its preparation in various forms—fresh and preserved, bottled, canned, and concentrated—has expanded greatly in recent decades, The product which has enjoyed the greatest success is canned frozen lemonade concentrate.  Lemon juice is also widely used in the preparation of proprietary soft drinks, generally bottled but sometimes canned.  Lemon juice possesses special dietetic and medicinal values associated with its vitamin content and even enjoys certain cosmetic uses.  In general, these latter uses require comparatively little fruit or juice.
      The principal byproducts obtained from the fruit are citric acid from the juice and pectin and lemon oil from the rind.  Pectin and lemon oil are currently of principal importance, because of the competition to citric acid from the juice provided by synthetic citric acid produced by controlled sugar fermentation, and have found a wide variety of industrial, culinary, and cosmetic uses.  A number of pharmaceutical products using the lemon have also been developed.  In California, however, the value of the return from byproducts has rarely, if ever, equalled the cost of fruit production.
      It seems likely that lemon culture will continue to decrease in relative importance in the citricultural world for the following reasons: (1) the lemon is not palatable as a fresh fruit; (2) its principal constituent, citric acid, can be produced synthetically at low cost; and (3) the returns from byproducts rarely equal the production cost of the raw material.
      Commercial lemon culture developed first in Italy, mainly in Sicily, and until a few decades ago that country led in production.  Steady and rapid increase in California, however, and a marked decrease in Italy because of the mal secco disease put the United States in the lead shortly before World War II.  In 1961-62, the California and Arizona crop was approximately 16.7 million boxes (76-1b) in comparison with 14.3 million boxes in Italy.  Acreage in California decreased by 23 per cent (11,500 acres) in the decade ending in 1964.  With both acreage and production increasing in Sicily, Italy had regained the leading position by the 1964-65 season.  The United States and Italy accounted for about three-fourths of the world crop of 48 million boxes in 1965.  Spain, Greece and Argentina each produced from 2 to 3 million boxes and Turkey, Lebanon, and Chile exceeded 1 million boxes.  There is some commercial production in virtually all of the other Mediterranean countries and also in Australia and South Africa.
      With respect to description and identification, the lemon presents especially difficult problems.  Not only is the fruit from a given bloom highly variable in its characteristics, but, as pointed out elsewhere, the fruit from different blooms commonly exhibits greater differences than those which occur between varieties in the same bloom.  Insofar as fruit characters are concerned, the varieties grown in California and many of those in the Mediterranean basin are remarkably alike, if not identical.  The principal exceptions are those, such as Interdonato of Italy and a few others, which are citron-like in certain characters and presumably of hybrid origin, and Arancino and Lunario of Italy and a few others of distinctive form.  Finally, the rind characteristics of the immature fresh lemon are materially modified during curing and storage.  As a consequence, for many if not most varieties, it is difficult to prepare accurate and meaningful fruit descriptions and virtually impossible to identify them from the fruits alone.
      Fortunately, however, the tree characteristics commonly exhibit greater differences than do the fruits and hence are useful in both description and identification.  Thus, the Lisbon tree in California is characterized by maximum growth vigor, thorniness, density of foliage, size, cold resistance, and production of a crop mainly in winter and spring.  By contrast the Eureka tree is considerably less vigorous, virtually thornless, less densely foliated, much smaller, markedly less cold-resistant, and less productive but more everbearing.  The bulk of the Eureka crop is produced in spring and summer.  The Eureka variety also has a marked tendency to produce the fruit in terminal clusters (fig. 4-75).  The characteristics of the Villafranca tree are intermediate between these two extremes though somewhat closer to Lisbon.  In California, therefore, where the clones presently employed virtually all trace back to these three varieties, tree characteristics are much more important in description and more useful in identification than fruit characters.
      All of those fruits that may be considered true lemons fall into two natural groups: the common or acid lemons and the sweet or low-acid lemons.  Both groups are characterized by purple coloration in the flower buds, new shoot growth, and chalazal spots.
      Pink-fleshed bud sports are known to have occurred in the acid lemon group, but the writer has been unable to discover any that have been named and propagated commercially.
      While some authorities would include the distinctive limettas of the Mediterranean, in the opinion of the writer these can best be regarded as a separate, closely related group and considered under C. limetta Risso.

      Major Acid Lemon Varieties.—The following varieties represent the acid lemons which the author considers of primary importance.

Allen
      See under Eureka.

Berna (Verna, Bernia, Vernia) (fig. 4-76)
      Fruit medium in size, oval to broad-elliptical; neck or collar short; nipple well developed.  Seed content variable, but usually few to none.  Color bright yellow at maturity.  Rind medium-thick (thinner in summer crop); surface somewhat pebbled, rough; tightly adherent.  Crop comes mainly in winter but holds well into summer, with undesirably large fruit, however.
      Tree very vigorous, upright-spreading, large, and productive.
      According to Gonzalez-Sicilia (1963) Berna is by far the most important Spanish variety, constituting more than 90 per cent of the acreage in the Levant.  It is grown also in Algeria and Morocco.  In California, both the fruit and tree are much like the Lisbon.

Bradbury
      See under Lisbon.

Cascade
      See under Eureka.

Cavers
      See under Lisbon.

Comune
      See under Femminello Ovale.

Cook
      See under Eureka.

Corona Foothill Eureka
      See under Villafranca.

Deaver
      See under Lisbon.

Eureka (fig. 4-75 and 4-77)
      Fruit medium-small, elliptical to oblong, sometimes obovate; commonly with short neck or low collar at base; usually short but sometimes long apical mammilla or nipple; frequently surrounded with areolar furrow.  Seed content variable but usually few to none.  Color yellow at maturity.  Rind medium-thick; surface finely pitted with sunken oil glands, slightly rugose, commonly with low longitudinal ridges; tightly adherent.  Segments about 10; axis small and usually solid.  Flesh color greenish-yellow; fine-grained, tender, juicy; flavor highly acid.  Crop well distributed throughout year, but mainly in late winter, spring, and early summer.
      Tree medium in vigor and size, spreading and open in growth habit, virtually thornless; sparsely foliated (in comparison with Lisbon and others); strongly everbearing and produces fruit at the ends of long branches (fig. 4-75); precocious; productive.  Tree lacking vigor compared with most other varieties; more sensitive to cold, insect infestation, and neglect; shorter-lived.
      The fruit of the Eureka variety differs in general from that of Lisbon, the principal other variety in California, in that it is more prominently ridged and has a somewhat rougher rind surface and usually a smaller and less pronounced nipple.  The tree differences are much more marked.  In addition to those differences mentioned earlier, the leaves are darker in color and less sharply pointed and the margins are somewhat more crenate than the Lisbon.
      The Eureka variety originated in Los Angeles, California, in a group of seedlings grown from fruit of Italian origin—the seed of which is said to have been planted in 1858.  Several years later Andrew Boyle and C. R. Workman acquired some of these seedlings and eventually they selected several that appeared to be promising.  About 1877, Workman provided Thomas A. Garey, a prominent Los Angeles nurseryman, with budwood from one of these seedlings and he propagated and introduced it under the name of Garey's Eureka (Butterfield, 1963).  Because of its precocity, thornlessness, and everbearing nature, it soon rivaled the Lisbon variety.  Both have remained the principal varieties in California and have achieved the status of major lemon varieties of the world.  Eureka ranks as a major variety in most important lemon-growing countries except Italy, Spain, and a few other Mediterranean areas.  Russo (1955), as a result of a study of varieties in California, recently expressed the opinion that Eureka has its ancestry in the Lunario variety of Italy.
      California nurserymen agree that the following clonal selections are currently the most popular: Allen, Cascade, Cook, Meek, Ross, and Wheatley or Thornton.  Within the limits of normal variation associated with environmental and disease factors, bud progenies from the parent trees of these selections are virtually indistinguishable with the exception of Ross, which is more vigorous than typical Eureka and differs in other respects.  It is probably best regarded as a separate variety of unknown origin.
      Presumably because of their greater vigor, caused in part at least by freedom from virus infection, the use of known or presumed nucellar clonal budlines during recent years has increased to the extent that virtually all Eureka lemon trees propagated in California are now seedling or nucellar clonal selections.  The only known nucellar line in use is Frost, originated by the geneticist and breeder, H. B. Frost, at the Citrus Research Center, Riverside, California.  What are presumed to be nucellar lines of some of the most popular clonal selections—Allen, Cook, Cascade, etc.—are now in use and others will soon become available.

Femminello Ovale (Comune, Ruvittaru)
      Fruit of medium size, short elliptical; rounded at base or very faintly necked; nipple low and blunt (much less prominent than in Sfusato); seeds comparatively few and mostly rudimentary.  Color yellow at maturity.  Rind medium-thick; surface finely pitted with depressed oil glands, moderately smooth; tightly adherent.  Segments about 10; axis of medium size and solid.  Flesh tender, juicy, and very highly acid.  Crop well distributed throughout year but mostly in late winter and spring.
      Tree of medium vigor and size, nearly thornless; leaves medium-sized; highly productive.  Especially well adapted to the forcing treatment.
      The oldest and still most important Italian lemon varieties belong to the Femminello group, which according to Burke (1962) accounts for approximately three-fourths of Italian production.  The Femminello varieties are characterized by a pronounced everblooming, everbearing habit which makes them especially responsive to the forcing or verdelli treatment so distinctive of Sicilian lemon culture.  The fruit is of good quality, suitable for both shipment fresh and processing, and the trees are moderately to highly vigorous, upright-spreading, and productive.  Unfortunately, with few exceptions, varieties of this group are susceptible to the mal secco disease.  The two most important varieties of this group are the older Sfusato (see below) and the newer Ovale or Comune.
      Because of its regular and abundant production, good shipping and storage quality, and adaptation to the verdelli treatment, Femminello Ovale has long been the principal Italian variety.  Unfortunately it is very susceptible to the mal secco disease.  The comparatively new Santa Teresa variety, which is somewhat similar to Ovale and thought to be a derivative of it, is said to have resistance to this disease.

Femminello Sfusato (Favazzina, Siracusa)
      Fruit of medium size, elliptical to oblong; prominently necked and with large long-tapering nipple; seedy.  Color yellow at maturity.  Rind medium-thick; surface finely pitted with sunken oil glands, medium smooth; tightly adherent.  Segments about 10; axis of medium size and semi-open.  Flesh firm, juicy, and highly acid.  Crop well distributed throughout year but mainly in late winter and spring.
      Tree very vigorous, upright-spreading, large, spiny; leaves large; highly productive.  Especially well adapted to the forcing treatment.
      Russo (1955) is of the opinion that the California Lisbon clones are remarkably similar to or identical with the Italian Femminello Sfusato.  Once highly important in Italy, this variety has largely been replaced by Femminello Ovale and others.

Fino
      See under Mesero.

Frost Eureka
      See under Eureka.

Gallego
      See under Lisbon.

Galligan
      See under Lisbon.

Hall
      See under Lisbon.

Interdonato (Speciale)
      Fruit large, oblong-cylindrical; collared or short-necked; truncate at apex; prominent sharp-pointed conical nipple surrounded by pronounced areolar furrow, commonly deeper on one side; seeds very few.  Color yellow at maturity.  Rind thin, very smooth, shining; tightly adherent.  Segments 8 to 9; axis medium-small and solid.  Flesh color greenish-yellow; crisp and juicy; flavor highly acid with slight bitterness.  Crop produced mainly in fall and early winter.  Earliest of Italian varieties.
      Tree vigorous, upright-spreading, usually thornless; foliage moderately dense.  Leaves large and somewhat citron-like, with round-pointed blades, undulate margins, and short wingless petioles.  Moderately productive but does not respond well to forcing treatment and hence grown primarily for early fruit.
      According to Burke (1962), the very distinctive Interdonato variety, which currently accounts for about 5 per cent of Italian production, has been planted solely because of its resistance to mal secco disease, to which its resistance is said to be intermediate between the Femminello and Monachello varieties.
      Interdonato is considered a lemon-citron hybrid and is said to have originated about 1875 on the property of a Colonel Interdonato in Nizza, Sicily.

Jameson
      See under Lisbon.

Kaweah
      See under Lisbon.

Ledig
      See under Lisbon.

Limoneira 8A
      See under Lisbon below.

Lisbon (fig. 4-78)
      Fruit medium in size, elliptical to oblong; base tapering to inconspicuous neck; apex tapering likewise into a usually large, prominent nipple surrounded by an irregular areolar furrow, commonly deeper on one side.  Seed content variable, but usually few to none.  Color yellow at maturity.  Rind medium-thick; surface finely pitted, faintly rugose, inconspicuously ribbed if at all; tightly adherent.  Segments about 10; core small and solid.  Flesh color pale greenish-yellow; fine-grained, tender, juicy; flavor very acid.  Crop comes mainly in winter and early spring.
      Tree vigorous, upright-spreading, large, thorny, densely foliated, and productive.  Tree most vigorous of varieties grown in California and most resistant to adverse conditions such as frost, heat, wind, and neglect.
      The Lisbon fruit is generally smoother and less ribbed than Eureka, the nipple and areolar furrow more prominent, and the taper at the ends more gradual.  The characters are so variable and overlapping, however, as to make identification from small samples uncertain, if not impossible.  The tree is quite different from the Eureka, however, and easily distinguishable.
      Lisbon is of Portuguese origin, although it is not known there by that name.  It is believed to be a selection of the Gallego seedling clonal group, which in Portugal is somewhat comparable to the common sweet orange groups of Spain, Italy, and numerous other countries.  A selection known as Portugal in Morocco and Algeria is said to be indistinguishable from the Lisbon introduced from California.²⁰
      The earliest reference to Lisbon in California appears to be its listing in the 1853 catalogue of Warren and Sons Nursery and Garden in Sacramento.  It was brought to California in 1849 or soon thereafter from Massachusetts by J. L. L. F. Warren, who had listed it in a nursery catalogue issued at Nonantum Vale, near Boston, as early as 1843 (Butterfield, 1963).  It is virtually certain that this variety ultimately reached southern California, for Caryl (1940) reports that budwood from an old Lisbon lemon tree growing in Alameda was shipped to S. P. Stowe of Goleta in 1883.
      Two importations are known to have been made from Australia, where this variety was introduced as early as 1824 (Bowman, 1955).  The first was by S. P. Stowe in 1874, who shared his introduction with Thomas A. Garey, a pioneer citrus nurseryman of Los Angeles.  The second was by J. W. North of Riverside, who received a few small trees in 1875 and turned them over to D. N. Burnham, a California nurseryman.
      The vigor, hardiness, and high productivity of Lisbon combined to establish its early and enduring popularity, particularly in the California interior districts.  Eureka has been its only rival, principally in the coastal districts, though in recent decades that variety has declined somewhat in popularity in favor of Lisbon.  Although not as widely grown as Eureka in most other lemon-producing countries, Lisbon is unquestionably one of the major varieties.
      It early became evident that in California this variety contained several clones which differed in vigor, size and abundance of thorns, compactness of branching, and denseness of foliage.  Principal among these selected for propagation were the so-called "short-thorn," "semidense," and "open" types as well as the "standard" clone characterized above.  Since Lisbon is not regarded as a clonal variety in its country of origin and at least three independent introductions contributed to its propagation in California, the facts strongly support the conclusion that these types or so-called "strains" were contained in the original introductions and that, as a consequence, Lisbon should properly be regarded as a group of clones in California, probably of common parentage, rather than a single clonal variety.  All of the clones currently propagated seem to be of the standard or short-thorn types, both of which are characterized by high vigor and productivity.
      In California, the selection of outstanding trees for use in propagation has been widely employed for some decades, which has made possible comparison of numerous individual tree bud progenies.  It is the consensus of the nurserymen that the old budline clonal selections currently most in demand are Galligan, Limoneira 8A, Monroe, Prior, Rosenberger, and Strong, and to a lesser extent Kaweah and Walker.  Selections of importance in the recent past include Bradbury, Cavers, Deaver, Hall, Jameson, Ledig, Price, Prospect, and USDA.  At the time of their selection, the bud parent trees were outstanding in vigor and productivity and were considered to be typical for the variety.
      With two possible exceptions—Galligan and Rosenberger—bud progenies are indistinguishable within the normal range of variation produced by environmental and disease factors.  Since the Galligan orchard was planted in 1886 with trees from Florida, which are said to have been ordered as Villafranca, the probability exists that this selection is of that variety.  There is general agreement, however, that Rosenberger differs appreciably from Lisbon in both fruit and tree characters and also from Galligan to a somewhat lesser degree.  Since its bud parentage is uncertain, the writer believes it is best to consider Rosenberger a separate variety of unknown origin.  In arriving at these conclusions, he is aware that they will be strongly contested by some authorities.²¹
      Within recent decades, the use of seedling clonal lines has become popular in California and is increasing.  The only known nucellar clonal budline of the Lisbon variety is Frost, which was produced by the geneticist and breeder H. B. Frost at the University of California Citrus Research Center, Riverside.  More recently, what are presumed to be nucellar lines have been obtained from some of the named oldline clonal selections.  A few of these have been propagated and currently are being planted.

Meek
      See under Eureka

Mesero (Primofiori, Fino)
      Fruit spherical to oval; nipple comparatively small and sharp-pointed; moderately seedy.  Paler in color thanBerna and rind smoother and thinner.  Also higher in juice and acid content.  Crop comes mainly in winter.
      Tree exceptionally vigorous, attaining large size, very thorny, and highly productive.  Foliage density and leaf size greater than Berna.
      This variety, of unknown Spanish origin, is said to be preferred by processors, but is much less extensively grown than Berna.  It should not be confused with the Primofiore of Italy which refers to fruit produced from the first or spring bloom.

Monachello (Moscatello)
      Fruit medium-small, elliptical but tapering at both ends; neck lacking; nipple small and inconspicuous; seeds few or none.  Color yellow at maturity.  Rind thin; surface smooth but with large sunken oil glands; very tightly adherent.  Segments about 10; axis medium-small and solid.  Flesh tender, somewhat lacking in juice, and acid content lower than most.  Crop well distributed throughout year but mainly in winter and spring.
      Tree somewhat lacking in vigor, slow growing, and round-topped; strongly drooping, slender, nearly thornless branches; dense foliage.  Leaves large, thick, with undulate margins, and brighter green than most lemons.  Fruit produced inside the foliage canopy.  Moderately productive in comparison with Femminello and well adapted to forcing but with markedly reduced winter crop.
      The outstanding virtue of this distinctive Italian variety is its resistance to mal secco disease.  This is the reason for its extensive planting some decades ago to the point where it was second only to Femminello.  In all other respects, it is inferior to Femminello and currently it is planted only in areas where mal secco is very severe.
      Certain characteristics of this variety, particularly the distinctive growth habit and cross-sectional shape of the larger branches, suggest that it is a lemon-citron hybrid.

Monroe
      See under Lisbon.

Moscatello
      See under Monachello.

Portugal
      See under Lisbon.

Price
      See under Lisbon.

Primofiori
      See under Mesero.

Prior
      See under Lisbon.

Prospect
      See under Lisbon.

Ruvittaru
      See under Femminello Ovale.

Siracusa
      See under Femminello Sfusato.

Speciale
      See under Interdonato.

Strong
      See under Lisbon.

Thornton
      See under Eureka.

USDA
      See under Lisbon.

Verna
      See under Berna.

Vernia
      See under Berna.

Villafranca
      Fruit indistinguishable from Eureka, but seasonal distribution of crop more like Lisbon, mainly in winter.
      Tree similar to Lisbon, but more open and less upright in growth habit, less thorny, and not as densely foliated.
      These characterizations are adapted from Webber (1943), since the original clone has been little propagated commercially in California, or elsewhere so far as can be ascertained, for many of decades.  Indeed, Villafranca is currently of so little importance as scarcely to warrant inclusion here.  The only reason for including it lies in the fact that certain clones with characteristics intermediate between Eureka and Lisbon have been propagated as selections of those varieties.  Almost certainly several of those currently of importance in California—notably the so-called Galligan Lisbon and Corona Foothill Eureka selections—are in reality Villafranca selections.  This may conceivably be true also of the popular so-called Rosenberger Lisbon and Ross Eureka selections.
      Said to be of Sicilian origin, the Villafranca variety was introduced into Florida by H. S. Sanford about 1875 and brought to California not long thereafter.

Wheatley
      See under Eureka.

      Minor Acid Lemon Varieties.—Acid lemon varieties of local importance or which possess distinctive characteristics suggesting promise for the future are presented below.

Amalfitana
      See under Lunario.

Arancino (Cucuzzaru)
      Arancino is one of a number of minor Italian varieties listed by Casella (1935a).  The highly distinctive fruit is nearly globose, with a very short nipple and thick rind, and very seedy.  The tree is vigorous, hardy, and compact, with small spines and leaves.  Arancino is very responsive to the forcing treatment under which the fruit occurs in clusters.

Armstrong (Armstrong Seedless)
      Both tree and fruit of this California variety are much like the Eureka, but Armstrong is more vigorous and less productive and the latter is less seedy (only occasionally a seed).  The budded parent tree came to notice about 1915 in the orchard of Sanford Johnson, Riverside, and is thought to represent an unwittingly propagated bud variation of Eureka.  It was called to the attention of A. D. Shamel of the U.S. Department of Agriculture in 1936 and was patented in 1939 (U.S. Patent No. 342) and introduced by the Armstrong Nurseries of Ontario.  Recommended as a home garden variety, it has not achieved much importance.

Asaasli (Saasli, Sakosli)
      Asaasli is a vigorous, productive variety of Lebanon and Syria.  It is said to have originated on the Island of Chios (Greece).  The tree resembles Lisbon and the fruit is somewhat like Eureka, but the crop occurs mainly in late winter and spring.

Assam
      See under Nepali Oblong.

Bonnie Brae
      Fruit medium-large, oblong to long elliptical-shaped; both neck and nipple usually lacking; moderately seedy.  Rind very thin, smooth, and leathery.  Flesh crisp and somewhat lacking in juice and acid.  Tree lacking in vigor and frost-sensitive.
      This California variety originated as a seedling from seed of Italian origin grown by H. M. Higgins near San Diego, who named and introduced it about 1880.  Although the fruit is highly attractive, it proved to be unsuitable for commercial culture.  This variety is now merely a collection item.

Corpaci
      Corpaci is a local Italian variety of interest only in the Simeni area near Siracusa.  The fruit has both a well-developed neck and nipple, is low in seed content, and matures earlier than most other varieties.  The tree is vigorous, thorny, and productive.

Cucuzzaru
      See under Arancino.

Frost Lisbon
      Frost is at present the only known nucellar selection of Lisbon available.  It was derived in 1917 by H. B. Frost of the Citrus Research Station, Riverside, and was released about 1950.  Seedling budlines presumed to be of nucellar origin have recently been derived from some of the most popular California clonal selections, however, and currently are being planted to some extent.

Genoa (Genova)
      Genoa is a California variety which Webber (1943) says is of the Eureka type and difficult to distinguish from it.  As the writer saw it in Chile, where it was taken from California and constitutes the principal variety, it appeared to be somewhat more vigorous, densely foliated, and cold-resistant.  It was introduced into California about 1875 from Genoa, Italy, by Jose Rubio of Los Angeles.  So far as the writer has been able to ascertain, it has achieved commercial importance only in Argentina and Chile.

Genova
      See under Genoa above.

Kusner
      Kusner is a vigorous, productive Russian variety said to have originated from the breeding program of the government research station at Sukhum, Georgia.  In California, it is indistinguishable from Lisbon or the Vernia introduced from Morocco.

Lambert Eureka
      This Australian chance seedling is indistinguishable from Eureka except that it is more vigorous and productive and hence is believed to be of nucellar origin.  Lambert was found by R. J. Benton, former government citrus specialist, about 1940 on the place of Horace Lambert, Moorland, New South Wales.  It is said to be highly promising as a replacement for old clonal selections.

Lo Porto
      The fruit of this new Italian variety is characterized by a globose form and a very large, fleshy calyx.  Lo Porto was found in Altarello di Baida, a village in the Conco d'Oro district of Sicily, during the course of a mal secco resistance survey.  It was first described by Crescimanno (1953), and is said to have considerable resistance.

Lunario (Amalfitano, Quatre Saisons) (fig. 4-79)
      Fruit medium-large, long elliptical to long-obovate; commonly with well-developed neck or furrowed collar; usually with narrow sharp-pointed nipple; seedy.  Rind smooth and medium-thin.  Flesh color greenish-yellow; not very juicy; only moderately acid.  Tree of medium vigor and size, strongly overbearing, thornless; foliage dark green; highly productive.
      Lunario is a distinctive Italian variety.  It is very responsive to the forcing treatment but the verdelli fruit is smaller in size, and the following winter crop is markedly reduced in amount.
      Lunario is of local importance in parts of Sicily and the Amalfi area near Naples and is grown to some extent in Libya, Tunisia, and Algeria.

Malti
      This is a Lebanese variety of unknown origin.  The tree is moderately vigorous, thorny, and productive, and the fruit resembles the Lisbon.  The crop comes mainly in fall and winter.  The Malta lemon of northern India is probably the same variety.

Nepali Oblong (Assam, Pat Nebu or Nimbu)
      Fruit medium large, long elliptic to oblong-obovate; base rounded; nipple broad but low.  Rind medium-thick, firm; surface very smooth, shining; clor greenish-yellow.  Segments about 11 and axis hollow.  Flesh color greenish-yellow; fine-textured, juicy; not very acid.  Seeds few to none.
      Tree vigorous, spreading with flat and open crown of drooping, nearly spineless branches; foliage citron-like.  Everbearing.
      Nepali Oblong is the principal native so-called lemon of India and is said to have originated in Assam (Bhattachariya and Dutta, 1956).  Both tree and fruit exhibit numerous citron characters.

Pat Nebu or Nimbu
      See under Nepali Oblong above.

Quatre Saisons
      See under Lunario.

Real
      This Spanish variety produces a very large, oblong, thick-rinded, highly seedy fruit of low juice content and medium acidity.  It is locally important in the vicinity of Málaga.

Rosenberger
      Rosenberger is a vigorous, highly productive clone that is currently popular in California.  While commonly considered to be of the short-thorn Lisbon type, the fruit is shorter, plumper, and more truncate at the base, and there are minor tree differences.  Rosenberger also differs somewhat, although less so, from what is considered to be true Villafranca.  As a consequence and because of its importance, the writer considers it best to give Rosenberger varietal standing.  It traces back to an old orchard owned by W. B. Cavers at Upland, which is said to have consisted of both Lisbon and Villafranca trees.  It was named for the Rosenberger orchard of the same locality, where its outstanding performance attracted attention.

Ross (Ross 10-1)
      Ross is a vigorous, productive clone that has been popular in recent decades in California.  While commonly referred to as a selection of Eureka, from which the fruit is indistinguishable, the tree is more vigorous and densely foliated, and there are other minor differences.  Because of these differences and its current importance, it seems best to give Ross varietal standing.  The parent tree was selected from a group of similar trees in an orchard owned by W. G. Ross at Escondido and planted in 1913.  The bud parentage is unknown.

Saasli
      See under Asaasli.

Sakosli
      See under Asaasli.

Santa Teresa
      This comparatively new Italian selection of the Femminello Ovale type is considered to be highly promising because of its greater resistance to the mal secco disease than any other clone found thus far.  The parent tree was an old disease-free tree discovered in a Femminello orchard that had almost been destroyed by the disease (Russo, 1955).  It is said to be the variety currently most planted as a replacement in areas of Italy where the disease is severe.

      Ornamental Lemon Varieties.—Clones which exhibit variegation in the leaves or fruit, or both, have occurred as limb sports and some of the most stable of these have been propagated for use as ornamentals.  One of the best of these ornamentals is the Variegated Prior Lisbon.  Perhaps the most interesting ornamental, however, is the variegated, pink-fleshed lemon.  At least two such clones have come to notice—one of Eureka in California and another of unknown origin in the Mediterranean (Citron Sanguin Panaché).

      Sweet Lemon Varieties.—The writer is acquainted with only one named variety of the true sweet lemon—Dorshapo—but has seen this same fruit in Tunisia under the name of citron doux, where it is grown to some extent and much appreciated by the Arab population.  In Tunisia, it commands higher prices than common lemons.  Moreover, Chapot (1963d) states that it occurs, although not commonly, in Morocco and Turkey and doubtless elsewhere in the Mediterranean.  He has reported (1963d) the remarkable fact that this clone regularly produces a few normally acid fruits and some in which the individual fruits contain both acid and sweet juice sacs or vesicles.  Chapot postulates chimeral natures of the clone as the probable cause.
      Webber (1943) placed the Millsweet limetta with the sweet lemons, but the writer has included that fruit with the other limettas.  The pani-jamir of Assam (Bhatachariya and Dutta, 1956) appears to be a true sweet lemon.

Dorshapo
      Fruit much like Eureka but slightly more ribbed; nipple somewhat more prominent; areolar furrow commonly deeper on one side.  Flesh color amber-yellow; sweet, insipid, and lacking the typical flavor of the sweet lime.  Acidity very low but not completely lacking.
      Tree much like Eureka, but more vigorous, thornier, and less productive.  Flower buds and young shoot growth purplish-red tinted.
      This variety was introduced into the United States from Brazil in 1914 and was named for the introducers—(Dor)sett, (Sha)mel and (Po)penoe of the U.S. Department of Agriculture.

      Fruits Resembling the Lemon.—Some of the lemon varieties, as previously noted, exhibit characteristics of citron to a certain degree.  This appears true of Monachello, Interdonato and Francescano of Italy, San Jeronimo of Spain, and Nepali Oblong and other lemons of India (Randhawa, Singh, and Choudhury 1960).  Since the lemon characteristics are predominant and such fruits are grown and marketed as lemons, these varieties were included with the true lemons.
      A lemon-like fruit in which characters of the sweet citron are evident is the peretta (C. peretta Risso).  It is large, ellipsoid in form, and with pronounced neck and prominent nipple.  The rind is thick and citron-like and the flavor sweet and insipid.  Peretta is an old variety of Italy and the French Riviera.  It is of minor importance and grown only in dooryard plantings.
      There are other fruits, however, in which lemon characters are evident but the differences are such as to warrant their separate classification.  Among the most important of these are jamberi or rough lemon, the karna, and the galgal or hill lemon of India, the Meyer lemon, and the limettas, which are discussed separately in the next subsection.

Alemow or Colo (C. macrophylla Wester) (fig. 4-80)
      Fruit medium-large, oblong to obovate; often with prominent mammilla surrounded by circular furrow; seedy.  Rind medium-thick (for size of fruit); surface somewhat rough and bumpy; tightly adherent; color greenish-yellow.  Segments numerous (about 15); central axis large and solid.  Flesh color greenish-yellow; low in juice; strongly acid and bitter.  Seeds polyembryonic.
      Tree vigorous, spreading, very thorny (with short stout spines); flowers and new growth strongly purple-tinted.  Leaves small to medium, pale green, narrow elliptical, blunt-pointed, and with broadly winged petioles of the pummelo type.
      Lemon or lime characters in the alemow are discernible, and there is some suggestion of pummelo.  The writer has provisionally placed the alemow in this group, and it is included in this treatment because of its promise as a lemon rootstock in California where the soluble salt and boron content of the soils is unfavorably high for the commonly used rootstocks.  Alemow is said to be native to the Island of Cebu, Philippine Islands.

Citronelle
      See under Rough Lemon.

Colo
      See under Alemow.

Estes
      See under Rough Lemon.

Galgal or Gulgul (C. pseudolimoni Tan.) (fig. 4-81)
      Fruit medium-large to large, oblong to ellipsoid; low, sometimes furrowed collar or neck; usually with short blunt-pointed nipple, sometimes depressed and flat.  Rind medium-thick; surface usually smooth but sometimes moderately rough; tightly adherent; color pale to golden yellow.  Segments about 10; axis large and hollow.  Flesh color pale yellow; coarse in texture, moderately juicy; flavor very sour and with trace of bitterness.  Seeds numerous and large.
      Tree vigorous, upright or spreading but irregular and open, with stout branches, numerous thick spines; leaves large and dull-green, resembling the sweet lime in form and tendency to rolling or cupping.  Flowers large, purple-tinged, and produced in spring only.  New shoot growth purple-tinted.
      This Indian citrus fruit of ancient and unknown origin is also known as the hill lemon or Kumaon lemon.  While resemblances to the lemon are obvious, there are notable differences, among which are the essential oils and hence the aroma of both leaves and rind, and the single bloom, one-crop behavior.  Moreover, the tree is more resistant to both cold and heat.
      The galgal has commercial importance only in submontane areas along the Himalayas and in parts of the Punjab where it is grown as a substitute for the lemon or lime.  Several unnamed clones are propagated commercially, including an acidless form.

Gulgul
      See under Galgal above.

Jamberi
      See under Rough Lemon.

Karna (Kharna Khatta, Karna Nimbu, Khatta Nimbu) [C. karna Raf.] (See fig. 4-82)
      Fruit medium to medium large, of variable form but in general round to oval; usually with broad and prominent nipple, sometimes depressed or lacking.  Rind moderately thick, firm; surface smooth, warty or ribbed; tightly adherent; color golden yellow to deep orange.  Segments about 11; axis medium-large and semi-hollow to solid.  Flesh color dull orange; coarse-textured, only moderately juicy; flavor acid with faint aroma suggestive of sour orange.  Seeds numerous, somewhat slimy, and moderately polyembryonic.
      Tree vigorous, medium to large in size, upright-spreading, spiny; foliage lemon-like but darker green.  New growth purple-tinted.  Flowers medium-large and strongly purple-tinged.  One bloom and crop per year.
      Karna is an old Indian fruit of unknown origin, and almost certainly a natural hybrid.  While the tree and fruit are distinctive, they exhibit characters of both rough lemon and sour or bitter orange, and there are also characters suggestive of the acid citron.  The commercial importance of karna arises solely from the fact that it is extensively employed in India as a rootstock, second only to rough lemon.

Karna Khatta
      See under Karna above.

Khatta Nimbu
      See under Karna above.

Kumaon Lemon
      See under Galgal.

Mazoe Lemon
      See under Rough Lemon.

Meyer Lemon (C. meyeri Y. Tan.) (fig. 4-83)
      Fruit medium in size, oblong to short elliptical, sometimes faintly ribbed; base rounded, sometimes faintly necked and radially furrowed; apex rounded or with low, broad nipple.  Rind thin, soft; surface very smooth; tightly adherent; color yellowish-orange to orange.  Segments about 10; axis small and solid.  Flesh color light orange-yellow; tender, very juicy; lemon-flavored and acid.  Moderately seedy.  Crop distributed somewhat throughout the year but mainly in winter.
      Tree moderately vigorous, small to medium in size, spreading, nearly thornless, hardy, and productive.  Flowers and new shoot [sic] purple-tinted.  More or less everflowering but mainly in spring.
      The Meyer lemon compares favorably with the sweet orange for both cold and heat resistance and thus has a much wider range of climatic adaptation than either the common lemon or lime for which it is used as a substitute.  The fruit is remarkably affected by climatic factors and differs greatly in appearance in different regions.
      This fruit was found near Peking, China, by the plant explorer Frank N. Meyer of the U.S. Department of Agriculture and introduced in 1908.  Because of its obvious resemblances to the lemon and its suitability as a substitute for that fruit, it has come to be known as the Meyer lemon.
      Introduced as a promising ornamental, it rapidly increased in popularity and soon fulfilled the most sanguine expectations.  It has become one of the most widely used citrus fruits as a dooryard plant and is especially adapted for use potted or tubbed.  Unfortunately, however, its use is currently banned in some citrus areas because of the hazard it is considered to present as a symptomless carrier of certain viruses, particularly tristeza.  Virus-free clones, several of which are currently available, will doubtless replace those employed in the past and thus preserve this useful and attractive ornamental.
      Although acceptable as a lemon substitute for home use, the Meyer lemon has not proven satisfactory as a commercial variety for the fresh-fruit trade.  The fruit is too tender and juicy to withstand handling, shipping, and storage without excessive waste.  Moreover, it does not cure or color well during storage, nor is it acceptable to most consumers when lemons are available.  As a consequence, it has failed to establish itself as a commercial variety of more than local importance anywhere.  Meyer lemon was planted fairly extensively in Texas, South Africa, and New Zealand, but appears to have declined in favor since World War II.  In Florida, however, some interest has been shown in it as a possible lemon substitute for local markets and for processing.

Milam
      See under Rough Lemon below.

Rough Lemon (Jamberi, Jatti Khatti, Mazoe Lemon, Citronelle) [C. jambhiri Lush.] (fig. 4-84)
      Fruit medium in size, of highly variable form but usually oblate to elliptic-oblong; commonly with irregularly furrowed or lobed basal collar or neck; usually with broad apical nipple surrounded by a deep irregular areolar furrow.  Rind medium-thick; surface typically deeply pitted, and rough or bumpy, sometimes ribbed; easily separable; color lemon-yellow to brownish-orange.  Segments about 10; axis large and hollow.  Flesh color light yellow to pale orange; medium juicy; flavor moderately acid.  Seeds numerous, small, highly polyembryonic, and cotyledons faintly green.  Some crop throughout the year but mainly in winter.
      Tree vigorous and large, upright-spreading, with numerous small thorns; leaves medium-small, blunt-pointed, and light green.  Flowers small and mandarin-like, purple-tinged, and produced more or less throughout year, but mainly in spring and late summer.  New shoot growth faintly purple-tinted.  Sensitivity to cold about like that of true lemons.
      This species exhibits a remarkable range of variation in fruit characters, and in India, where it is native, four relatively distinct types are recognized, one of which is similar to the form obtained from Italy known as C. volckameriana (for description see Chapot, 1965a).  There is also a sweet-fleshed form.
      Presumably native to northeastern India, where it still grows wild, the rough lemon seems to have been taken to southeast Africa by the Portuguese toward the end of the fifteenth or early sixteenth century and thence to Europe.  It doubtless reached the New World not long thereafter.
      Although used to some extent as a lemon substitute, for which it is not very suitable, the rough lemon is highly important as a rootstock in many parts of the world—notably India, South Africa, Australia, Argentina, Brazil, and Florida.  In the last two mentioned countries, selections have recently been named—Estes and Milam—which exhibit resistance to the burrowing nematode.
      While resemblances to the lemon are fairly obvious, the differences are greater, and many of its characters are clearly those of the Rangpur or mandarin.

      The Limettas (C. limetta Risso).—There are three remarkably similar and evidently closely related lemon-like fruits which, in the opinion of the writer, constitute a natural group, probably best designated as the limettas—namely, the Millsweet so-called sweet lemon, the Mediterranean or Tunisian (to distinguish it from the Indian or Palestinian) sweet lime and the Moroccan limetta or Marrakech limonette.  The last fruit is comparatively little known and not until recently has an adequate description become available (Chapot, 1962a).  All three fruits are obviously closely related to the lemon but exhibit differences in common that indicate close interrelationship and common ancestry.
      Within the range of normal variation, the trees are indistinguishable except that the Mediterranean sweet lime does not exhibit pink coloration in the flower-buds, flowers, and young shoot growth.  Moreover, the fruits do not exhibit significant external differences.  Internally, however, the following important differences are noted: Mediterranean sweet lime (limetta)—flesh acidless, chalazal spot cream-colored; Millsweet sweet lemon (limetta)—flesh low in acid, chalazal spot purple; Moroccan limetta—flesh highly acid, chalazal spot purple.
      Differences from the lemon, which set all three limettas apart as a group, include a characteristic oval-shaped, round-pointed, and usually somewhat cupped leaf, a highly distinctive fruit form, and an altogether different rind oil closely resembling that of the bergamot.
      In the writer's opinion, the limettas constitute a well defined group of which the Moroccan limetta (Marrakech limonette) may be considered to represent the normal acid form, the Millsweet limetta a low acid form (comparable to Dorshapo lemon), and the Mediterranean sweet limetta the acidless form.

Marrakech Limonette (Moroccan Limetta, Limoun Boussera)
      Fruit medium-sized, depressed subglobose, commonly ribbed; base rounded or somewhat flattened; apex strongly flattened with broad and deep areolar furrow surrounding a prominent nipple.  Rind thin, moderately pitted with sunken oil glands; somewhat bumpy; adherent; color light yellowish-orange.  Segments about 11; axis medium in size and open.  Flesh color pale yellow; juicy; very sour and aromatic.  Moderately seedy, moderately polyembryonic, and chalazal spot purple.
      Tree vigorous, large, upright-spreading and open, lightly spiny, and highly productive; leaves lemon-like, but more oval, less sharp-pointed, and usually somewhat cupped at upper end.  Flowers purple in the bud and new growth purple-tinted.  Flowers somewhat throughout the year but mainly in spring.
      According to Chapot (1969a), this fruit is confined to Morocco, where presumably it is native, and was first described by Guillaumin (1921).  It has little economic importance and is used mainly as an ornamental though also as a lemon substitute.

Mediterranean Sweet Limetta (Limetta de Tunisie, Limoncello, Arancio di Spagna)
      Fruit indistinguishable from Millsweet limetta except acidless, hence even more insipidly sweet; chalazal spot cream-colored instead of purple.
      Tree likewise indistinguishable except flowers not purple-tinged and young shoot growth not purple-tinted.  Flowers white and shoot growth green.
      The Mediterranean sweet limetta is an old and reasonably well-known fruit in the Mediterranean and has considerable importance in Tunisia and some localities in Italy.  In view of the few and minor differences between these two fruits, the confusion in the literature and otherwise is readily understandable but nevertheless unfortunate.  In addition, this fruit has often been confused with the Indian or Palestine sweet lime which it resembles only slightly.

Millsweet Limetta (fig. 4-85)
      Fruit virtually indistinguishable from Marrakech limonette except low in acidity and hence tastes sweet and may average somewhat smaller.
      Tree likewise indistinguishable, but perhaps somewhat less vigorous.
      This is an old, comparatively little-known fruit in the Mediterranean, but it must have originated there for it was early brought to California, presumably from Mexico.  Lelong (1888) quotes General Vallejo as remembering having eaten the "sweet lemon" at Monterey in 1822 and having seen trees of it that same year growing at the San Gabriel Mission.  Webber named it Millsweet and described it as a sweet lemon variety in 1943.

Limes

      The group name for the limes is lime in English and French and lima in Italian and Spanish.  In Arabic-speaking countries and the Orient, the limes and lemons are generally grouped together under the term limûn (limoon, limoun) for the former and nimbu or limbu (numerous modifications) for the latter.
      Like the citron and lemon, the limes are believed to have originated in northeastern India, adjoining portions of Burma, or northern Malaysia and to have followed the same general path westward to the Mediterranean basin and thence to the Western Hemisphere.  Because of their grouping with the other acid citrus fruits, however, it is difficult, if not impossible, accurately to trace and time their westward distribution (see chap. 1, this work).  It is virtually certain that the sour lime was among the fruits taken by the Arabs across North Africa into Spain and Portugal and highly probable that it was also taken to Italy by the Crusaders, although it seems not to have persisted long in Europe.  It is known to have been brought to the Americas by the Spanish and Portuguese explorers in the early part of the sixteenth century, where it escaped from cultivation and became feral in parts of the West Indies, some Caribbean countries, and southern Florida.
      While exhibiting certain basic similarities, the true limes constitute a highly varied group of which the members differ so significantly that separate species standing appears to be justified.  They fall into two natural groups, however, the acid or sour limes and the acidless or sweet limes.  The acid limes include small-fruited and large-fruited kinds and varieties.
      While similarities exist between the small-fruited and large-fruited acid limes, the differences are much greater.  Moreover, there are marked differences in climatic tolerances and reactions as well as in resistance or susceptibility to certain diseases.  Their separation into different species seems therefore justified.
      The tree differences are notable.  Thus, the West Indian lime is less vigorous and robust than the Tahiti, much finer-stemmed, very much thornier, and has much smaller leaves of a distinctly paler color.  It is much more cold-sensitive (about like the citron) and requires more heat to develop good fruit size.  In contrast with the Tahiti lime, it is highly susceptible to the withertip fungus (Gloeosporium limetticolum), citrus canker (Xanthomonas citri), and the tristeza virus, for which it is currently the most widely used indicator plant.  It is markedly resistant to the citrus scab fungus (Elsinoë fawcetti).
      The fruit differences are less marked, but in addition to the larger size of fruit the Tahiti group is virtually or entirely seedless, and the odor, while similar, is less pronounced.  The flavor, though about equally acid, lacks the strong pungency and aroma of the West Indian lime.
      Except in the United States, the commercial lime industry is restricted to the West Indian group, which is markedly cold-sensitive and has a high total heat requirement for the production of fruit of good size.  Consequently, the lime industry has developed principally in hot semitropical, subtropical, or tropical regions.  Indeed, this fruit is without a doubt the most tropical of the commercially important citrus fruits.  When grown in cooler regions, such as southern California, the West Indian lime is undesirably small and is discounted in the markets.  It has also been observed that the climates most favorable for this lime are likely to be poorly suited to lemon culture and that where good limes are available they are generally preferred to lemons.  These facts are believed to explain why the major lime-producing countries and regions are India, Mexico, Egypt, and the West Indies.  Although statistics are not available, almost certainly India is the largest center of lime culture.  Lime growing is widespread in the central and southern portions of that country, and the fruit is used extensively.  The 1965 crops for Mexico and Egypt were reported at approximately 3.1 and 1.4 million boxes, respectively, and production for the West Indies was estimated at 400,000 boxes.  World production in 1967 was doubtless in the range of 8 to 10 million boxes.  A considerable part of the Mexican crop is exported to the United States to supplement the Tahiti limes grown in Florida and California.
      Although it is known that the West Indian lime was planted on some of the Florida Keys (reef islands off the southeast coast) as early as 1838 and that ultimately it became naturalized there (hence the term Key lime), it was not until the early part of the present century that a small commercial industry was developed in Florida.  It was short-lived, however, and suffered a reverse from the disastrous hurricane of 1926, from which it never recovered.  Early introduced into southern California by the Spanish mission fathers, attempts at its commercial culture invariably resulted in failure and were abandoned many years ago.
      Unusual or distinctive practices employed in the culture of this fruit include the almost universal use of seedlings rather than budded trees and a forcing treatment for the production of summer fruit in the Faiyûm oasis, a major center of lime production in Egypt.  It is similar to the verdelli treatment employed in Sicily to increase the summer lemon crop.
      Of all the citrus fruits, the West Indian lime is highest in percentage composition for acid in the juice, ranging from 7 to 8 per cent (calculated as citric).  It is somewhat lower than the lemon in ascorbic acid, however, and in other vitamins and hence has somewhat less dietetic value.  For many years, however, sour lime juice (probably sweet lime also) was used in the treatment or prevention of scurvy.
      Much the greater part of the crop is marketed and consumed fresh, its uses being similar to those of the lemon.  It is especially esteemed for the making of limeade and carbonated beverages and as a constituent of and garnish for alcoholic drinks.  In the Orient, it is extensively used for pickling and in culinary and medicinal preparations.  In the West Indies and to some extent elsewhere, a considerable part of the crop has been used in the manufacture of bottled lime juice, which is highly prized as a constituent of mixed alcoholic drinks.  The principal byproduct is lime oil.
      Commercial culture of the Tahiti or Persian lime is much more recent and less important and currently is confined to the United States where, because of its cold-hardiness and lower heat requirement, it is much better adapted than the better known and generally preferred West Indian lime (fig. 4-86).  Since the limes succeed much better than the lemon in humid climates the industry is almost entirely confined to Southern Florida, where its comparatively low heat requirement causes this fruit to attain acceptable maturity during the summer months—the period of greatest market demand and best prices for the acid citrus fruits.  California does not possess this advantage because of a much later season of maturity.  In Florida, the Persian lime is therefore a rather acceptable substitute for the preferred Mexican lime.  Because it approaches the lemon in size, it was early found necessary to educate the markets to accept this fruit as a true lime rather than a small lemon, but this prejudice seems now largely to have been overcome.  The 1965 Florida crop of approximately 560,000 boxes was reported to have been produced from 3,500 bearing acres.  There were about 500 acres in California in 1965.  A considerable part of the Florida crop of Persian limes is processed into frozen concentrate limeade and lime juice.  Lime oil is a by-product.
      The fruit-handling practices are much like those employed for lemons.  The fruit is picked to size and hence being largely immature must undergo some storage and curing prior to packing and shipping.

      Small-fruited Acid Limes (Citrus aurantifolia Swing.).—A species description of the small-fruited acid limes would correspond in general to that given below under West Indian lime.  However, several types of this fruit are recognized in India which differ in size, form, and degree of seediness.  Spineless forms also occur in India, have been found in the Mediterranean, and are reported elsewhere.  The most interesting of these forms to the writer is the large-fruited, long-elliptical form known as Abhayapuri Kaghzi, which is grown commercially in Assam (Bhattacharya and Dutta, 1956) and adjoining portions of West Bengal and East Pakistan and found in the markets of Calcutta.  So far as can be ascertained, however, only the form described below has attained commercial importance elsewhere.

West Indian (Mexican, Key) (fig. 4-87)
      Fruit very small, round, obovate or short-elliptical; base usually rounded but sometimes with slight neck; apex also rounded but usually with small, low, and faintly furrowed nipple.  Moderately seedy and highly polyembryonic.  Rind very thin; surface smooth, leathery; tightly adherent; color greenish-yellow at maturity, following which it drops from the tree.  Segments 10 to 12; axis very small and usually solid.  Flesh color greenish-yellow; fine-grained, tender, juicy; highly acid with distinctive aroma.  Somewhat everbearing but crop comes mainly in winter (earlier in very hot climates).
      Tree medium in vigor and size, spreading and bushy with numerous, slender, willowy fine-stemmed branchlets densely armed with small, slender spines.  Foliage dense and consists of small, pale green, broadly lanceolate, blunt-pointed leaves with definitely winged petioles.  Flower buds and flowers small, and flowering occurs throughout year but mainly in spring and late summer.  Not withstanding contrary statements in the literature, the new shoot growth is faintly purple-tinted and flower buds and young flowers faintly purple-tinged.  Coloration fades rapidly, however, especially if the weather is warm, and is soon lost.  Very sensitive to cold.
      The West Indian or Mexican lime is the kaghzi nimbu (numerous modifications and other local names) of India, the limûn baladi of Egypt, the doc of Morocco, the Gallego lime of Brazil, and limon corriente in some Latin American counties.  In North America, it is sometimes also called the Key lime.
      Because of the relatively high degree of polyembryony exhibited by this fruit, it comes remarkably true to seed, and seed propagation is still employed in most of the countries where its culture is important—India, Egypt, and Mexico.  As a consequence, clonal varieties have not been selected and named, except for a few which are noted below.  In this connection, it is significant to note that in California it has been found impossible to distinguish between seedling clones of the common acid lime from India, Egypt, and Mexico, and clones of Florida and West Indian from origin budded trees.  It seems likely, therefore, that the principal clones employed are genetically identical and that only one horticultural variety is involved, which in California is known as Mexican and in Florida as West Indian or Key.
      A nucellar seedling selection arising from the Mexican lime-grapefruit cross was described and named Everglade in 1905 by Webber (1943) in the belief that it produced a larger fruit.  In California, it has been indistinguishable from the parent clones and therefore has not come into use.  Thornless clones reported in the literature include: Doc Sans Epines (Doc Thornless) of Morocco; Yung, a form introduced into California from Morroco by George Yung about 1882 and described and named by Webber (1943); an introduction from Trinidad (West Indies) received by the United States Department of Agriculture in 1910, a limb sport which was found in the Ballard orchard near Weslaco, Texas, shortly after the freeze of 1925; and a selection recently made at Yuma, Arizona, by J. Hamilton of the U.S. Department of Agriculture.  None has proved to have commercial value.
      Because they produce distinctive symptoms when infested with the tristeza virus, West Indian lime seedlings are widely used as an indicator in the detection of this disease.

      Large-fruited Acid Limes (Citrus latifolia Tan.)—The two most important large-fruited acid limes are the Tahiti and the Bearss, which are described below.

Tahiti (Persian)
      Fruit medium-small (like small lemon), oval, obovate, oblong or short-elliptical; base usually rounded but sometimes slight necked and faintly furrowed; apex rounded; areolar area elevated into a low nipple.  Seeds are or lacking.  Rind thin; surface smooth, tightly adherent; color pale lemon-yellow at maturity.  Segments about 10; axis small and usually solid.  Flesh color pale greenish-yellow; tender, juicy; very acid and with true lime flavor.  Somewhat everbearing, mainly in winter (earlier in hot climates such as southern Florida).  If left on tree past maturity, some fruits develop a peculiar breakdown in the areolar area at the stylar end.
      Tree vigorous, broad-spreading, drooping, medium to medium-large, nearly thornless; foliage dense green.  Leaves medium in size, broadly lanceolate, and petioles winged.  Flower buds and flowers medium in size and flowering occurs throughout year, mainly in spring.  Purple coloration usually faint and evanescent in both flowers and shoots.  Fully as cold-resistant as the true lemons.
      The origin of the Tahiti or Persian lime is unknown, and its history is obscure.  The name Tahiti arises from the fact that this type of lime was introduced in California from Tahiti sometime during the period of 1850 to 1880.  As the Persian lime, it was introduced into Australia as early as 1824 (Bowman, 1955), possibly from Brazil, since it is mentioned in connection with the Celeta (Seleta) and Bahia orange varieties of that country.  The origin of the name Persian is unknown, however, although it seems likely that this fruit came to the Mediterranean area via Persia as did the citron.  Currently, it is not to be found in Persia, however (Chapot, 1965b).  The Sakhesli lime of the island of Djerba (Tunisia) is clearly of the same type and has been grown there for a long time, presumably centuries.  H. Chapot, the distinguished French citrus systematist, reports that he has also seen old trees of this fruit in Algeria and that the name Sakhesli means "from Sakhos," an Arabic name for the island of Chios (Greece).²²
      While the only commercial variety of the Tahiti lime apparently produces no viable pollen and is normally seedless, Reece and Childs (1962) succeeded in obtaining 250 seeds from a commercial canning plant in Florida from which 140 seedlings were planted in an orchard and 77 survived and ultimately fruited.  A high degree of monoembryony is indicated as only two seedlings proved to be indistinguishable from the parent clone.  The remaining seedlings exhibited a very wide range in species characters, but approximately 60 per cent were predominantly citron, lemon, or seedy acid lime.  From these data, Reece and Childs concluded that this lime is clearly of hybrid origin, that one parent is obviously the common acid lime, and that the other is either lemon or citron, but probably the latter.  It is interesting that they were unable to observe more than 18 chromosomes, the normal diploid number for the genus, whereas Bacchi (1940) reported this lime as triploid in genetic constitution.
      While further study will be required to make certain of the facts, it appears that there are presently several horticultural clones of Tahiti or Persian lime, only one of which is commercially important.

Bearss (Bearss Seedless, Persian) (fig. 4-88)
      Both tree and fruit of the Bearss variety correspond closely with the Tahiti description.  The flowers are devoid of viable pollen also, contain exceedingly few functional ovules, and the fruits are regularly seedless.  The Bearss variety is triploid in its genetic constitution (Bacchi, 1940).  Moreover, the comparatively rare seeds which occur are highly monoembryonic also.
      According to Webber (1943), this variety originated about 1895 on the place of T. J. Bearss, a nurseryman at Porterville, California.  While the facts are unknown, it presumably occurred as a seedling of a tree grown from seed from a fruit of Tahitian origin.  It seems first to have been described and illustrated by Lelong (1902) and was introduced and promoted by the Fancher Creek Nursery Company of Fresno in 1905.  Although the Tahiti lime was reported to be growing in Florida as early as 1883 (Ziegler and Wolfe, 1961), it is not known when Bearss was introduced there.  Moreover, the present lime industry in Florida is based on a variety known as Persian.  For many years, therefore, it appeared that the two varieties were different though obviously similar.  Comparisons conducted in California, however, although not wholly satisfactory because of complicating disease factors, strongly support the conclusion that the two clones are identical.  If this is indeed the case, it seems highly probable that this variety originated considerably earlier than Webber reports.
      Found about 1934 by G. L. Polk in Homestead, Florida, and introduced in 1941 (U.S. Plant Patent No. 444) is the derivative, smaller, round-fruited variety, named Idemor, which occurred as a limb sport.  More recently, what appears to be a similar mutation has been reported in a Bearss tree in Morocco.  Idemor has not achieved commercial importance.

      Other Large-fruited Acid Limes.—Webber (1943) described the Pond variety, which he obtained in Hawaii in 1914.  It appears to closely resemble Bearss, though he reports minor differences.  The Sakhesli lime of Tunisia also closely resembles Bearss but is obviously a much older variety.  An unnamed clone introduced by the U.S. Department of Agriculture and described as a seedless lime of Italian origin is of interest since it appears to be intermediate between the Mexican and Bearss limes, although somewhat more resembling the latter.

      Sweet Lime (Citrus limettioides Tan.).—The flavor of sweet limes seems insipid to people in the United States but is apparently pleasing in certain other countries.  The Indian or Palestine sweet lime is described below.

Indian (Palestine) (fig. 4-89)
      Fruit medium in size, subglobose to oblong or short-elliptic, sometimes faintly ribbed; base evenly rounded; apex commonly rounded; areolar area often protruded into a low, flat nipple surrounded by a shallow circular furrow.  Seeds few, highly polyembryonic; chalazal spot light tan (almost blond); cotyledons faint green.  Rind thin to very thin; surface smooth to very smooth with prominent oil glands flush with surface; tightly adherent; color greenish to orange yellow at maturity.  Aroma of rind oil distinctive.  Segments about 10; axis medium in size and semi-hollow at maturity.  Flesh color straw-yellow; tender, very juicy; flavor insipid because of lack of acid, and with slightly bitter aftertaste.  Single bloom and crop.
      Tree distinctive in appearance, medium-large in size and of spreading but irregular growth habit, with thick, thorny branches; foliage medium-dense.  Leaves pale green, medium in size, long-oval, blunt-pointed, and characteristically cupped or rolled, with petioles wing-margined rather than winged as in most limes.  Flowers medium-large, pure white, and new shoot growth pure green.
      The Indian sweet lime is the mitha nimbu (numerous modifications and other local names) of India, the limûn helou or succari of Egypt, and the Palestine sweet lime (to distinguish it from the Millsweet and Tunisian limettas, commonly called sweet limes).
      In India, where this fruit has been grown longer than elsewhere, several forms are recognized that differ principally in fruit shape, presence or absence of the nipple, and in fruitfulness.  In northeastern India, to which it is native, it has been established (Hodgson, Singh and Singh, 1963) that the soh synteng of Assam is the acid form of this fruit.  It is similar in all respects except: (1) the fruit is highly acid; (2) at a limited and ephemoral [sic] stage pink coloration is present in the flower buds and new shoots; and (3) the color of the chalazal spot is pinkish-purple.
      The Indian sweet lime and the Tahiti lime bear slight resemblances to the galgal or hill lemon of India and the Tunisian limetta.  There are virtually no resemblances to the small-fruited acid lime.
      In California, this sweet lime is remarkably affected by climatic influences.  Desert-grown fruit differs so greatly in size, color, form, and rind texture from that produced in the cool, equable coastal region that the inexperienced observer would consider them to be different fruits.
      The sweet lime is much esteemed in India, the Near East, Egypt, and Latin America and is considered to have special medicinal values in the prevention and treatment of fevers and liver complaints.  Statistics are not available, but the sweet lime is grown commercially in northern India and Egypt and widely elsewhere as a garden plant.  It is also a rootstock of considerable importance in parts of India and of major importance in Israel and Palestine.
      The most unusual practice of horticultural interest in the culture of this fruit is the universal use of rooted-cutting trees in Egypt, whereas seedling trees are most commonly used elsewhere.
      The Tunisian limetta has been classed as a sweet lime but in the opinion of the writer is more logically considered an acidless member of the limetta group (C. limetta).  It resembles the Indian sweet lime only in flavor and the tendency to cupping of the leaves.  The essential oil of the rind is altogether different in aroma and typical of the other limettas, as are all the other characters.
      Columbia appears to be the best known named clonal selection of the sweet lime.

      Fruits Resembling the Limes.—Synthetic hybrids producing fruits that resemble the limes thus far seem to have been restricted to the West Indian lime and include the lemonimes (lemon X lime) and limequats (lime X kumquat).
      Of the lemonimes only Perrine (West Indian lime X Genoa lemon) seems worthy of mention and it has not achieved commercial importance.  Although classed and described by Webber (1943) as a lemon, in the opinion of the writer it has greater resemblance to and behaves more like the West Indian lime.  While the fruit is somewhat larger and the tree is said to be resistant to both lime withertip and citrus scab, its claimed cold resistance has been found to be insufficient for southern Florida, where some years ago it was planted as a substitute for the West Indian lime.  A freeze wiped out the plantings, which were then replaced by the much hardier Persian lime.  Perrine originated as a hybrid made by W. T. Swingle and associates of the U.S. Department of Agriculture in 1909 and was named and described in 1931.
      Of the limequats, which are bigeneric hybrids, three varieties have been named (for description see Webber, 1943, pp. 667-68)—Eustis (fig. 4-90), Lakeland, and Tavares.  Their importance is approximately in that order.  All are characterized by fruits that closely resemble the West Indian lime in size, form, and composition and hence are reasonably acceptable substitutes.  Eustis and Lakeland also closely approach the West Indian lime in color.  Tavares, however, exhibits some of the orange coloration characteristic of the kumquat and the pink coloration of the flower buds which occurs in the West Indian lime.  All of the limequats are more cold-resistant than the lime parent but considerably less so than the kumquat.
      None of the limequats has achieved commercial importance for the fruit, but Eustis and Lakeland are grown somewhat as ornamentals.  In California, they are popular as potted or tubbed plants for patios and terraces.
      Eustis and Lakeland are sister hybrids of the West Indian lime and the round kumquat (Fortunella japonica), and Tavares is a similar hybrid with the oval kumquat (Fortunella margarita).  They were made by W. T. Swingle of the U.S. Department of Agriculture in Florida in 1909 and were named and described in 1913.
      In India, where natural hybrids abound, there are a number of fruits in which lime parentage is fairly obvious.  The writer observed several natural hybrids in which both citron and kaghzi nimbu characters were evident.  There are also a number of fruits that appear to be lemonimes, among which the most important are the so-called Rajamundry and Baramasi lemons.  The former seems clearly to be a large-fruited lemonime of the West Indian lime type and the latter a thornless Tahiti lime-like plant and fruit.

THE KUMQUATS (FORTUNELLA SPECIES)
      Although the derivation is not given, Webber (1943, p. 639) states that the name kumquat (cumquat) is supposed to have come from the earliest known Chinese name, chin kan, which is translated as meaning "gold orange." In Japan, where this fruit has been grown for centuries, the name kin kan is said to have the same meaning.  A generalized description is presented below:
      Fruit tiny to very small, globose, obovate, oblong or oval; color golden yellow to reddish-orange; seeds few and with green cotyledons.  Rind medium-thick (for the size of the fruit); fleshy; surface smooth; sweet flavored but aromatic and spicy; tightly adherent; axis small and solid.  Flesh color yellowish-orange; juice scanty; flavor moderately acid.  Early midseason in maturity.  Fruit holds well on tree with little loss in quality.
      Plant an evergreen shrub or small tree (except on certain vigorous rootstocks), fine-stemmed and bushy, symmetrical, usually with few or no thorns; dense foliage consisting of small mandarin-like leaves (fig. 4-91).  Common species strongly cold-resistant.
      Markedly resembling the other citrus fruits in general and obviously closely related to the Calamondin and some of the small-fruited mandarins, the kumquats were included in the genus Citrus until comparatively recently when Swingle established the genus Fortunella (Swingle, 1915), which was soon accorded virtually universal acceptance.  The principal differences on the basis of which the separation was made (chap. 3, this work) included the following: (1) ovary locules many fewer than Citrus (three to five, rarely six or seven); (2) not more than two collateral ovules per locule (as compared to four to twelve); (3) stigma very broadly cavernous; (4) fruits very small with sweet, edible, more or less pulpy rind; and (5) small, more or less angular flower buds.
      Undoubtedly of Chinese origin and mentioned by earlier writers, the first description of the common kumquats appears to be that of Han Yen-chih, written in 1178 A.D. and translated by Hagerty in 1923, in which he refers to two kinds of chin kan (kumquat).  It seems probable that in European literature the kumquat was the fruit referred to by Ferrari (1646) as the "aurantium…minusculum, Kin kiu" described by the Portuguese missionary Alvarus Semedus who had spent many years in China.  So far as can be determined, this fruit (Nagami or oval form) was first introduced into Europe in 1846 by Robert Fortune, a plant explorer and collector for the London Horticultural Society, who found it in China (Fortune, 1846).  it must have been sent to the United States soon thereafter, for it is described and illustrated in the February, 1850, edition of Downing's Horticulturist (Webber, 1943, p. 640).  The round-fruited form Marumi was introduced from Japan into Florida in 1885, and the Meiwa and Hongkong kumquats were brought in by the U.S. Department of Agriculture between 1910 and 1912 (Webber, 1943).  So far as the writer has been able to ascertain, the Malayan kumquat, F. polyandra, remains to be successfully established in Europe or the United States.
      The common kumquats (Nagami and Marumi forms) exhibit two distinctive and significant climatic reactions concerned with temperature requirement.  Since growth activity occurs only at relatively high temperatures, the trees remain inactive and semidormant in subtropical and warm temperate climates during the fall, winter, and spring months and exhibit growth activity only during the comparatively short summer-growing season.  As a consequence, they normally come into bloom much later than Citrus species and enter the condition of induced dormancy earlier.  To judge from the behavior of the oranges and mandarins, this long period of growth inactivity coupled with photosynthetic activity must contribute materially to their outstanding cold-hardiness.  Whatever the reasons may be, however, these two kumquats exceed the hardiest of the citrus species in resistance to winter cold, including even the satsuma mandarins.
      On the other hand, the size attained by the fruit is materially affected by the amount of heat during the growing season and somewhat by the atmospheric humidity.  Thus, the fruit is larger, juicier, and less acid in Florida than in California, and similar differences exist between fruit grown in the hot interior districts of the latter state and in the cool, equable coastal region.
      Although the peel is edible, and the fruit may therefore be eaten whole, the taste is too tart for most palates.  The kumquat is largely used therefore for preserving in syrup, candying, and making marmalade.  Perhaps the principal use in the United States, however, is for decorative purposes and in gift packages of other citrus fruits, the preparation and sale of which constitutes an enterprise of considerable importance in Florida.  Since the tree is hardy, dwarfed and symmetrical, the foliage attractive, and the fruit small, brightly colored, and persistent, the kumquats have been prized and much used as ornamentals from time immemorial andthis doubtless is their most important use.  On dwarfing rootstocks, principally the trifoliate orange, they are long-lived and make excellent tubbed plants for terraces and patios in subtropical and warm temperate regions and conservatories elsewhere.
      The kumquats are most widely grown in China, southern Japan, and Taiwan (Formosa), though the tropical form is confined principally to Malaya.  Elsewhere their culture occurs mainly in the United States—in Florida primarily for the fruit for use in the gift-package trade and in California almost exclusively for use as ornamental plants.

Kumquat Varieties

      Presumably because of the fact that the seedlings are usually weak-growing and inferior, most of the horticultural varieties—in the Occident at least—are in fact the species clones originally introduced.  Swingle (chap. 3, this work) recognized four species, but Tanaka (1954) considers that there are six.  The differences between several of these species are so minor, however, as to cast doubt on the validity of some of them.  Listed in their probable descending order of importance, they are as follows:

Nagami or Oval Kumquat (F. margarita [Lour.] Swing.) (figs. 4-91 and 4-92)
      This species is the Naga or Nagami kinkan of Japan.  According to Swingle (chap. 3, this work), the most distinctive features of this species are the oblong, obovate, or oval form of the fruit, the narrow range in number of segments (normally four or five), the deep color and pronounced flavor of both fruit and rind, and the comparatively large leaf and tree.
      As previously indicated, this is the form which first reached the Occident.  It is vigorous and prolific and the fruit is deeply colored, pleasantly flavored, and of good size, though the rind oil is somewhat more pronounced than in other kumquats.  It is much the most popular variety both in the Orient and the United States.

Meiwa or Large Round Kumquat (F. crassifolia Swing.) (fig. 4-93)
      This species is the Ninpo, Meiwa or Neiha kinkan of Japan.  The most distinctive features of this kumquat are the short oblong to round form and relatively large size of the fruit, the more numerous sections (commonly seven), the very thick and sweet rind and comparatively sweet flavor, and the low seed content (many fruits are seedless).
      While Swingle originally (1915) considered it to be a valid species, he later concluded that this variety is a natural hybrid between the oval and round kumquats (chap. 3, this work).
      It is much the best variety for eating fresh and is reported to be widely grown in Chekiang Province of China and to some extent in Fukuoka Prefecture of Japan.  Meiwa is said to be slightly less cold-hardy than Nagami but is increasing in popularity in the United States.
      Tanaka reports the existence in Japan of a variegated form with striped fruits, which is a most attractive ornamentals.²³

Marumi or Round Kumquat (F. japonica [Thumb.] Swing.)
      This is the Maru or Marumi kinkan of Japan.  In comparison with the oval kumquat, which it closely resembles, the fruit of this kumquat is round or slightly oblate, sometimes obovate, and smaller, with a thinner and somewhat sweeter rind and a wider range in the number of segments (four to seven).  The tree is less vigorous and somewhat thorny, with smaller, less sharply pointed leaves (chap. 3, this work).

Hongkong Kumquat (F. hindsii [Champ.] Swing.) (fig. 4-94)
      This is the Mame or Hime kinkan of Japan.  According to Swingle (chap. 3, this work), this species grows wild in Hongkong and in the Chekiang and Kwangtung provinces of China.  The most distinctive features include the small size and spiny nature of the plant and the very small, brilliantly colored, subglobose, virtually inedible fruits that contain three or four segments and relatively large, plump seeds.  Since the pollen-mother cells contain double the normal number of chromosomes, Swingle considers it to have originated as an autotetraploid.
      The Hong Kong kumquat is apparently of ancient origin, for it is rather widely distributed in the wild and is undoubtedly the chin chu (golden bean) or shan chin kan (mountain golden mandarin) described by Han Yen-chih in 1178 A.D. and referred to by an earlier writer whom he quotes.
      In modern times, however, the name golden bean kumquat has been restricted to a cultivated diploid form, the chin tou of China or Kinzu kinkan of Japan, which Swingle considers to have originated from the wild species.  According to Swingle (chap. 3, this work), it differs from the parent species principally in having larger, thinner, and narrower leaves, shorter and more slender spines, and somewhat larger fruits.  The flowers are also smaller.
      It may be of interest to note that the fruits of the Hongkong kumquat appear to be the smallest of the true citrus fruits.
      While the Chinese are said to prize these fruits and to preserve them for use as a spicy flavoring, elsewhere they are merely novelty ornamentals, grown primarily as potted plants.

Changshou Kumquat (F. obovata Tan.)
      The Choju kinkan or Changshou or Fukushu kumquat of Japan is a dwarf variety that is reported to be widely grown as a potted plant in China and also in Japan to some extent.  According to Swingle (chap. 3, this work), it is characterized by the broadly obovate form of the fruit, a markedly depressed apex, medium size, thin rind (for a kumquat), and a rather large number of segments (five or six, sometimes as many as eight).  Seeds are usually few and polyembryonic.  The plant is small and thornless.
      This species was established by Tanaka (1933, p. 38) but was not accepted by Swingle who considered it to be a chance hybrid between two of the Fortunella species.

Malayan Kumquat (F. polyandra [Ridl.] Tan.)
      This little known kumquat appears to be of Malayan origin, for its present distribution seems to be restricted to that general region and Hainan Island.  According to Swingle (chap 3, p, 332), it is a thornless shrub with long, slender, lanceolate leaves and relatively large, round, and thin-skinned fruits (for a kumquat), containing five or six segments.  Swingle accepted this species, though he questioned its validity and suggested the likelihood of hybrid origin.
      It appears to be grown both for the fruit and as an ornamental but not as a potted plant.

Kumquat Hybrids

      Because of its marked cold-hardiness, the kumquat was early employed in the citrus fruit breeding program of the U.S. Department of Agriculture in Florida, and in 1909 a series of crosses was begun which resulted in the creation of the limequats, orangequats, citrangequats, and other hybrids.  Only the limequats and citrangequats have proven to have horticultural value.  Since the former more resemble the lime and are used as substitutes for it, they are treated with the limes.  The citrangequats, however, which are trigeneric hybrids in which a bigeneric citrange is one of the parents, most resemble the kumquat and hence are included here.
      In this connection, it should perhaps be mentioned that Swingle (chap. 3, this work) regards the kumquat as one of the parents of the Calamondin.

      The Orangequat (Fortunella sp. X mandarin).—The name given to this class of hybrid is misleading since its parentage involves a mandarin rather than a true orange (C. sinensis or C. aurantium).  So far as the writer has been able to ascertain, only one cross was made and one variety named (chap. 3, this work).

Nippon
      Fruit small (but larger than the kumquat), broadly oval to obovate; orange-colored; rind relatively thick and spongy; flavor mild and pulp acid.  Matures early but holds well on tree for several months.
      Tree slow-growing, medium-small, spreading; foliage dark green.
      This variety originated from a cross between the satsuma mandarin (C. unshiu) and the Meiwa kumquat (F. crassifolia)made in Washington, D.C. by Eugene May of the U.S. Department of Agriculture.  It was described in 1931 (Swingle, Robinson, and Savage, 1931) and introduced in 1932.  Although it is a somewhat attractive ornamental and the fruit makes excellent marmalade, the orangequat has not become popular and remains an oddity or collection item.

      The Citrangequats (Fortunella sp. X citrange).—Combining the cold-hardiness of the kumquat and trifoliate orange, the citrangequats appear to be more cold-resistant than the citranges or the Calamondin and kumquat, for they are said to succeed in regions too cold for these fruits (Ziegler and Wolfe, 1961, p. 63).
      Three varieties are described by Webber (1943, pp. 665-66), all of which produce fruits with marked resemblances to the kumquat and two of which are characterized by a high percentage of trifoliolate leaves.

Sinton (fig. 4-95)
      Fruit small, round to oval; often necked; color deep reddish orange; sharply acid; nearly seedless.  Tree moderately vigorous, upright, nearly thornless; leaves mainly unifoliolate.
      This Oval kumquat and Rusk citrange hybrid first fruited at Sinton, Texas, and was named and described in 1923 (Swingle and Robinson, 1923, p. 235).  It is an attractive ornamental and the fruit is beautifully colored but highly acid.

Telfair
      Fruit small, round; color yellow to orange-yellow; strongly acid; seeds few.
      Tree vigorous, upright, thorny; leaves variable but mainly trifoliolate.
      This is an Oval kumquat and Willits citrange hybrid, which first fruited in Telfair County, Georgia.  It was made in 1909 and named and described in 1923 (Swingle and Robinson, 1923, p. 234).

Thomasville
      Fruit medium-small, globose to oval; color yellow to orange-yellow; acid until fully mature when it becomes edible; somewhat seedy.
      Tree very vigorous, upright, thorny; leaves variable but mainly trifoliolate.
      This citrangequat is of the same parentage as Telfair and was first fruited at Thomasville, Georgia.  The cross was made in 1909, and the variety was named and described in 1923 (Swingle and Robinson, 1923, p. 230).
      Presumably because of the larger size and edibility of the fruit, it is much the most popular variety.

THE TRIFOLIATE ORANGE (PONCIRUS TRIFOLIATA [L.] RAFINESQUE)
      It is most unfortunate that there is no distinctive Occidental common name for this fruit—the karatachi of Japan—for it is completely inedible and remarkably different from the orange, so much so that it cannot properly be regarded as an orange in any respect.  Indeed it is included in this treatment only because: (1) trifoliate orange and some of its hybrids provide valuable rootstock varieties; and (2) the fruits of some of the hybrids approach edibility.
      The plant is a highly distinctive deciduous shrub or small tree with very large stout spines and small compound leaves with winged petioles and three leaflets.  In the smaller stems, the pith is discontinuous, in the form of transverse plates (continuous in Citrus and Fortunella).  The flower buds are small, single, lateral, protected by small fleshy scales, and are formed early in the summer preceding bloom.  The flowers are very short-stalked with five white, thin, papery petals, numerous stamens of which the filaments are free, and a compound pistil.  The ovary of the pistil is highly pubescent and contains six to eight locules, commonly seven.
      The fruits are small, oblate or obovoid to globose, and dull lemon-yellow.  The rind is relatively thick, soft, densely pubescent, and has abundant oil glands.  The juice is scanty and acid and the somewhat slimy pulp contains numerous droplets of acrid oil which impart a highly unpleasant taste.  The seeds are plump and polyembryonic.  The fruit normally ripens in late summer or early fall and drops soon thereafter, though off-bloom fruit may mature later.
      Climatically, this fruit belongs to the warm-temperate group, for it is nearly as cold-hardy as the Oriental persimmon and some of the peaches and Japanese plums.  The rest in the flower buds is comparatively light, however, and in subtropical climates is sometimes broken by excessively hot fall weather, with resultant bloom.  Trifoliate orange normally blossoms with the earliest deciduous fruit trees.  When used as a rootstock for the evergreen citrus fruits and kumquats, the trifoliate orange seems to accentuate their normal self-induced dormancy and to somewhat enhance their natural cold-hardiness, presumably because of its deciduous nature and hence true dormancy during late summer, fall, and winter.  Probably because of its requirement for chilling, this fruit does not appear to be climatically adapted to either tropical or very hot subtropical climates with mild winters.  These facts serve to explain why the natural range of climatic adaptation of the trifoliate orange extends into regions much too cold for citrus fruits and why its use as a rootstock is largely restricted to the colder portions of the subtropics.
      Undoubtedly native to central or northern China, where it is widely distributed and has been grown for thousands of years, the trifoliate orange is thought to have reached Japan sometime around the eighth century (chap. 3, this work) [sic] The first known description of it and reference to its use as a rootstock occurs in Han Yen-chih's Chü Lu, written in 1178 A.D. and translated in 1923.  The writer has not been able to determine when the trifoliate orange reached Europe, but it is known that William Saunders of the U.S. Department of Agriculture received it from Japan in 1869.
      As an outdoor ornamental, this plant is commonly grown in the warm temperate regions of China, Japan, western Europe, and eastern United States and is sometimes used as a hedge, for which it is very effective.  It has long been the most important rootstock in Japan, primarily for the satsuma mandarins, and increasingly is being employed in Australia, California, and Argentina.  However, it is susceptible to the exocortis virus, which has been found to be widely prevalent in citrus clones.  It is said that from ancient times the Chinese have used preparations of the fruit for medicinal purposes.
      Although the genus Poncirus was established by Rafinesque in 1815 (Ziegler and Wolfe, 1961), Linnaeus included it in the genus Citrus.  It was not until a hundred years later that Swingle gained acceptance for its restoration to separate standing.  Only one species is recognized, trifoliata, which André in 1885 designated as triptera.  As a consequence, until comparatively recently the trifoliate orange has been referred to as Citrus triptera in the French literature.  The existence of two groups with respect to flower size—the small-flowered and large-flowered—has long been recognized.  In California, the former seems to have a somewhat higher temperature requirement for growth and enters the rest, matures the fruit, and becomes dormant much earlier, which may be associated with its greater cold resistance when used as a rootstock.  In Japan, where this rootstock is extensively employed, it is believed that the large-flowered forms are more dwarfing (Bitters, 1964), but this has not been confirmed in California.

Rootstock Trifoliate Selections

      Because of renewed interest in the use of trifoliate orange rootstock, notably in California where it affords important advantages, during recent decades collections have been made of materials assembled from different parts of the world or recovered from outstanding local orchard trees.  While years will be required for their evaluation for use as rootstocks, comparison of nursery progenies clearly indicates the existence of a number of clones, some of which may ultimately justify naming as horticultural varieties.
      At the present time, however, the only clone in California whose behavior is sufficiently well established to warrant naming is Rubidoux (fig. 4-96).  The parent tree of Rubidoux was planted on the old Rubidoux site of the University of California Citrus Research Center, Riverside, about 1907 and came from the R. M. Teague Nursery Company at San Dimas, California.  While it belongs to the small-flowered group and has medium vigor in comparison with others, the writer knows of no other distinctive characteristics useful in its description or identification, though there may be such.

Ornamental Trifoliate Varieties

      Several dwarfed ornamental varieties are said to exist in the Orient.  According to Swingle (chap. 3, this work), the most important and interesting of these is the Japanese hiryo or Flying Dragon variety, which he introduced to the United States in 1915.  Grown primarily as a potted plant, this is a highly dwarfed variety with very small leaves, the leaflets of which are commonly reduced to linear filaments, and slender crooked branches armed with large, downward-curved spines.  It is a curious monstrosity which he has accepted—unnecessarily, in the opinion of the writer—as the botanical variety monstrosa of T. Ito.

Trifoliate Hybrids

      Although remarkable different from Citrus in nearly all respects, Poncirus hybridizes freely with the citrus species.  Because of its outstanding cold-hardiness, it was early used in the citrus breeding program of the U.S. Department of Agriculture.  Beginning in Florida in 1897 and continuing for several decades, many crosses were made between the trifoliate orange and citrus species and some with other genera.  From this work came a series of bigeneric hybrids—the citranges, citrumelos, citrandarins, citremons, citradias, and citrumquats—a few of which are of horticultural importance or promise.

      The Citranges (Poncirus X C. sinensis).—The influence of the trifoliate orange is strongly marked in the citranges as evidenced by the trifoliolate nature of their leaves, the acidity and bitterness of their fruits, and the cold-hardiness of the trees.  The influence of the sweet orange is shown, however, in the evergreen nature of the trees, though a few are semi-deciduous, and in their greater vigor.  Additionally, the fruit is usually much larger and more orange-like in appearance.  In general, however, the citranges exhibit some degree of intermediacy between the parental species.  Of great horticultural importance in connection with their use as rootstocks is the fact that with few exceptions they come remarkably true from seed.  They are highly polyembryonic and apparently rarely develop zygotic embryos (Swingle, 1927).
      The term citrange was announced and the first variety named and described in 1904 (Webber and Swingle, 1905) and subsequently a dozen or more have been added.  For descriptions of most of them the reader is referred to Webber (1943, pp. 656-65) and the literature he cites.
      In Webber's opinion, the citrange varieties that most closely approach the sweet orange in size, appearance, and edibility in the fresh state, and hence may be useful as juice fruits for dooryard planting in regions too cold for oranges and mandarins, are Morton, Coleman, and Savage.  He also recommends them as ornamentals.
      Since, in general, the citranges exhibit some of the most desirable features of the trifoliate orange combined with the greater vigor and wider range of soil adaptation of the sweet orange, some of them are currently of promise or already have achieved importance as rootstocks.  Principal among these are Carrizo, Rusk, and Troyer, which are described below.

Carrizo
      Carrizo is indistinguishable from Troyer and of the same parentage.  Savage and Gardner (1965) have recently presented convincing evidence that Carrizo and Troyer are in fact a single clone which originated as the zygotic seedling (CPB 4-5019) from a cross of Washington navel and trifoliate orange made by the senior author in 1909 under the direction of W. T. Swingle of the U.S. Department of Agriculture instead of two sister seedlings as had been assumed (Mortensen, 1954).
      In 1923, Swingle had 200 seedlings of this then unnamed clone sent to the Winter Haven substation (No. 19) near Carrizo Springs, Texas.  In 1938, he suggested it be named Carrizo, either forgetting that he had already given it the name Troyer in 1934, which seems unlikely, or because he failed to recognize its identity, which seems surprising.
      Bitters reports that its field performance has differed somewhat from Troyer, which is difficult to understand in light of the conclusions set forth above.²⁴

Rusk (fig. 4-97)
      Fruit rather small, oblate to spherical; smooth and virtually glabrous; color deep orange with reddish flush.  Rind thin and tightly adherent; segments about 10.  Flesh color orange-yellow; very juicy; flavor sprightly acid and only slightly bitter.  Seeds few and highly polyembryonic.  Early in maturity.
      Tree vigorous, tall-growing, productive, and hardy; foliage evergreen to semi-deciduous and dense, consisting of moderately large trifoliolate leaves.
      Rusk, a Ruby orange and trifoliata hybrid, is one of the oldest citranges, having been created by Swingle in 1897 and described and released in 1905 (Webber and Swingle).  It was named in honor of J. M. Rusk, the first Secretary of Agriculture of the United States.
      The tree is an attractive ornamental and the fruit is juicy and approaches edibility more closely than most citranges.  Its low seed content mitigates against use as a rootstock.
      Rusk is currently of greatest interest and importance in Florida.

Troyer (fig. 4-98)
      Fruit small, oblate to spherical; smooth and nearly glabrous; color light orange.  Rind medium-thick, with numerous oilglands; tightly adherent.  Segments 9 to 10 and axis solid.  Flesh color light yellow; juicy; flavor strongly acid and bitter.  Seeds numerous, plump, and highly polyembryonic.  Season of maturity early.
      Tree vigorous, upright-spreading, and medium-large with rather slender, thorny branchlets; foliage moderately dense, evergreen to semi-evergreen.  Leaves dark green, medium in size, and mainlytrifoliolate, occasionally unifoliolate.  Productive and hardy.
      This variety originated as a hybrid of the Washington navel orange crossed with trifoliate orange pollen (hence is actually a citruvel) that was made by E. M. Savage, under the direction of W. T. Swingle of the U.S. Department of Agriculture, at Riverside, California, in 1909.  In 1934, Swingle named it for A. M. Troyer, on whose place at Fairhope, Alabama, it was first fruited.  The rise of this rootstock to prominence in California has been spectacular.  Within less than twenty-five years from the first field trial it has become the rootstock most employed and is much in demand elsewhere.

      Other Trifoliate Hybrids.—Of the complex hybrids in which a citrange is one of the parents, currently only the citrangequats (Fortunella X citrange) have sufficient horticultural value to be worthy of mention.  Since they most resemble the kumquat parent, they are included under Fortunella.
      While several citrumelos (Poncirus X C. paradisi), citrandarins (Poncirus X C. reticulata and other mandarin species) and citremons (Poncirus X C. limon) are currently under trial as rootstocks and for other purposes, in the opinion of the writer none of the named or otherwise designated clones is currently sufficiently important to warrant inclusion in this treatment, some of them appear to be promising.

ACKNOWLEDGMENTS
      Rather obviously, it would have been impossible to prepare this treatise without the invaluable assistance so generously provided by colleagues both at home and abroad.  Indeed, for the degree to which it may have achieved its objectives of breadth of scope, accuracy, and adequacy, the credit is largely theirs.  Principal among those to whom grateful acknowledgment is made are the following:
      United States: F. E. Gardner and P. C. Reece, U.S. Horticultural Station, Orlando, and A. P. Pieringer, Citrus Experiment Station, Lake Alfred, both in Florida; R. T. Brown, Plaquemines Parish Experiment Station, Port Sulphur, Louisiana; E. O. Olson, U.S. Horticultural Station, Weslaco, Texas; R. H. Hilgeman, Citrus Branch Station, Tempe, Arizona; and R. G. Platt and W. P. Bitters, Citrus Research Center, University of California, Riverside.
      West Indies: Egbert Tai, University of the West Indies, St. Augustin, Trinidad.
      South America: S. Moreira and A. A. Salibe, Instituto Agronomico, Campinas, São Paulo, Brazil; and E. Sartori, University of Buenos Aires, Buenos Aires, Argentina.
      Australia and New Zealand: E. C. Levitt and R. J. Benton, Department of Agriculture, Sydney, New South Wales; and W. A. Fletcher and H. M. Mouat, Department of Scientific and Industrial Research, Auckland, New Zealand.
      Japan: M. Nishiura, Horticultural Research Station, Okitsu; and Y. Tanaka, Citrus Experiment Station, Komagoe, both in Shizuoka Prefecture.
      South Africa: W. J. Basson and R. H. Marloth, Citrus and Subtropical Fruit Research Institute, Nelspruit, Eastern Transvaal.
      Mediterranean Basin: H. Chapot, Narenciye Arastirma Istayonu, Antalya, Turkey (for the entire basin); E. Gonzalez-Sicilia, Estación Naranjera de Levante, Burjasot, Spain; R. Khalidy, American University, Beirut, Lebanon; H. O. Ruck, Food and Agriculture Organization, Rome (for Israel); and L. El-Mahmoudi, Ministry of Agriculture, Orman-Giza, Egypt.  Special thanks are due to Dr. Henri Chapot for making available his vast knowledge of the varieties of the Mediterranean basin and Near East and for suggestions, criticisms, and many of the photographs employed herein.  Dr. Chapot is, without doubt, the principal worker in this field and the leading authority.
      Of those who so kindly reviewed the final manuscript, special gratitude for their very great helpfulness is expressed to W. P. Bitters and Walter Reuther, Department of Horticultural Science, Citrus Research Center, University of California, Riverside.  Deep appreciation is also expressed to Mr. Harry Lawton whose editorial review of the manuscript resulted in great improvements in organization, arrangement, and presentation of the text.
      The writer assumes responsibility for the errors that will be found and asks that they be brought to the attention of the editor in subsequent revisions.

LITERATURE CITED

2. Personal communication from A. A. Salibe to the author, dated May 25, 1964.

3. Letter to the writer from E. C. Levitt, government citrus specialist in New South Wales, dated May 7, 1963.

4. Letter to the writer from E. C. Levitt, government citrus specialist in New South Wales, dated May 18, 1964.

5. Letter to writer from H. Chapot, dated March 24, 1964.

6. Letter to the writer from H. Chapot, dated March 24, 1964.

7. Letter to the writer from H. Chapot, dated March 24, 1964.

8. Chapot and Huet (1964) recently reported differences in the shape of the seeds, which are deltoid with a pronounced beak at the chalazal end for the acidless oranges. They also noted minor differences in flesh color and aroma.

9. Also reported in a letter from E. Gonzalez-Sicilia to the writer, dated June 25, 1963.

10. Letter to the writer from H. Chapot, dated December 20, 1963.

11. Letter to the writer from E. Gonzalez-Sicilia, dated June 25, 1963.

12. Letter to the writer from H. Chapot, dated May 6, 1964.

13. Letter to the writer from M. Nishiura, National Horticultural Research Station, Okitsu, dated May 30, 1963.

14. Letter to the writer from M. Nishiura, dated May 30, 1963.

15. Letter to the editor from W. P. Bitters, dated August 6, 1965.

16. Letter to the writer from H. E. Wahlberg, dated August 5, 1964.

17. For a detailed discussion of these differences, the reader is referred to the excellent paper by Chapot (1950a).

18. Letter to the editor from W. P. Bitters, dated August 6, 1965.

19. Letter to the writer from E. C. Levitt, dated September 24, 1963.

20. Letter to the writer from H. Chapot, dated June 24, 1963.

21. Letter to the editor from W. P. Bitters, dated August 6, 1965.

22. Letter to the writer from H. Chapot, dated September 22, 1963.

23. Unpublished report to the writer from T. Tanaka, submitted in July, 1955.

24. Letter to the editor from W. P. Bitters, dated August 6, 1965.