(ancient name of a fragrant African wood, afterward transferred to the Citron). Rutacese. Citron. Lemon. Orange. Small evergreen, more or less spiny trees or shrubs, grown for their edible fruits, and also attractive in foliage and flower.

Leaves glandular-dotted, persistent, apparently simple (in reality unifoliate compound leaves), borne on more or less winged or margined petioles, which are usually articulated with the blade and at their attachment to the twig: spines usually present, borne singly at the side of the bud in the axils of the leaves: flowers clustered or rarely solitary in the axils of the leaves, or in small lateral or terminal cymes or panicles, white or pinkish purple in the bud; petals 5 (rarely 4 or 6) thick, strap-shaped, not clawed at the base, imbricated; stamens numerous (16-60, usually 20-40) at least four times as many as the petals, polyadelphous, cohering toward the bases in a few bundles; ovary 8-15-celled, with a prominent usually deciduous style containing as many tubes as there are cells in the ovary: fruit a hes-peridium, globose, oval or oblate-spheroid, the segments filled with juicy pulp composed of stalked pulp-vesicles; seeds 1-8 in a cell, oval or oblong, 1/4-3/4in. long, with a pergameneous testa and thick fleshy cotyledons, usually with adventive embryos arising as buds from the nucellar tissue of the mother plant.

Natives of tropical and Subtrop. Asia and the Malayan Archipelago. - Half a dozen species are commonly cult, and have given rise to very many varieties as well as numerous hybrids, making the delimitation of the species exceedingly difficult. See Citrange, Citron, Etrog, Grapefruit, Lemon, Lime, Limequat, Orange, Pomelo, Tangelo.

The nomenclature here followed is based on the writer's treatment of the species of Citrus in "Plantse Wilsonianae." The fewest possible number of changes have been made consistent with presenting a clear account of the genus. A careful study of Citrus and the genera most nearly related to it has shown that the trifoliate orange differs in so many and such important characters that it seems necessary to recognize it as a separate genus (Poncirus). The same is true of the kumquats and the Australian limes.

Key To The Species

a. Winged petiole nearly as large as the blade of the If.: seeds very large, thick: fruit rough, oval, lemon-yellow when ripe: flowers solitary.................. 9. ichangensis aa. Winged petiole much smaller than the blade of the leaves: seeds small or medium sized: flowers usually in clusters. b. Leaves apparently not jointed between blade and petiole, oblong-serrate; petiole wingless: flower-buds tinted reddish: fruit with a very thick peel, fragrant, pulp acid.............. 1. Medica bb. Leaves with an obvious joint between the blade and petiole, crenate: peel thin or only moderately thick.

C. flower-buds tinted reddish on outside: petioles merely margined: leaves

crenate: fruits oval, more or less apiculate..................... 2. Limonia cc. flower-buds white: petioles more or less winged. D. fruits oval, often slightly papillate, small, 1-1 1/2 in. diam., greenish-yellow when ripe, thin-skinned, smooth: flowers small: petioles plainly winged: leaves small, pallid above, crenate, more or less punctate, obtuse: spines short, very sharp.................. 3. aurantifolia dd. fruits globose, depressed globose, rarely oval or pyriform, never papillate, orange-colored, or if yellow, fruits large and thick-skinned. E. Size of fruit very large, pale yellow when ripe: twigs pubescent when young: petioles broadly winged............ 4. grandis

EE. Size of fruit medium or small, orange or orange-yellow. F. The fruits with a solid core and a light skin; pulp sweet: petioles slightly winged.. . 6. sinensis ff. The fruits with a hollow core when fully ripe, skin loose or, if tight, pulp acid and petioles broadly winged. a. Skin tight: petioles broadly winged: pulp acid.... 5. Aurantium gg. Skin loose: petioles only narrowly winged or margined. H. The fruit borne singly at tips of branches, small; segments 7-10, pulp very acid: leaves

pale beneath........ 8. mitis hh. The fruit borne in axils of the leaves; segments 8-15, pulp sweet: leaves dark green below..... 7. nobilis

1. Medica, Linn

(from Media whence the species first came to the notice of the ancient Greeks and Romans). Citron. Fig. 971. A shrub or small tree, with long irregular branches: thorns short, stout and stiff: Ivs. rather pale green, large, oblong, 4-6 or 7 in. long and 1 1/2~2 in. wide, bluntly rounded at the tip with serrate margins, not articulated with the petioles, which are wingless: flowers large, reddish tinted when in the bud, usually in terminal panicles, or clustered, in the axils of the Ivs.; petals large, white above, reddish purple below; stamens numerous, 30-40 or more; ovary tapering gradually into the often persistent style: fruit large, oval or oblong, 6-10 x 4-6 in., bluntly apiculate, often rough or bumpy, lemon-yellow when ripe; skin very thick, fragrant; pulp scanty, acid; seeds oval, smooth, white inside. - The citron is very sensitive to cold because of its ability to grow at low temperatures, which causes it to start into a fresh and very tender growth after a few days of warm weather in winter. It is cult, in the Medit. region, especially in Corsica, whence large quantities of the peel are exported in brine to Amer. to be candied. The candied peel is much used in confectionery and in cakes.

Sparingly cult, in Calif, and Fla. A number of ill-defined varieties are grown, the most important being the Corsican, introduced from Corsica in 1894 by David Fairchild. The Etrog or sacred Jewish citron is grown in Corfu. See Citron.

Variety sarcodactylis, Swingle (Citrus sarcoddctylis v.

Fingered citron.   Citrus Medica variety sarcodactylis. (X 1/3)

Fig. 973. Fingered citron. - Citrus Medica variety sarcodactylis. (X 1/3)

Nooten. C. Medica variety digilata, Auct., not Lour.). Fo Shu Kan (Chinese). Bushukan (Japanese). Fig. 973. Differs from the common citron in having the segments of the fruit separated into finger-like processes. The fruits are very fragrant and are used by the Chinese and Japanese for perfuming rooms and clothing. It is sometimes grown as a dwarf potted plant for ornament. It should be introduced into this country.