(Last Modified On 5/13/2013)
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(Last Modified On 5/13/2013)
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Genus
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Citharexylum L.
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PlaceOfPublication
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Sp. PI. 625. 1753
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Synonym
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Rauwolfia Ruiz & Pav., Fl. Peru. 2: 26, pl. 152. 1799, non Rauvolfia L., Gen. PI., ed. 5. 1754. Scleroon Benth. ex Lindl., Bot. Reg. 29: Misc. 65-66. 1843. Cacocalyx S. Wats., Proc. Amer. Acad. Arts 24: 67. 1889.
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Description
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Trees or shrubs, rarely climbing; branches and branchlets usually tetragonal, sometimes spiny; leaf-scars mostly large, corky, and elevated, borne on more or less prominent sterigmata. Leaves deciduous, decussate-opposite, ternate, or verticillate, rarely approximate, subopposite, or even alternate, entire or dentate, usually bearing a pair of prominent glands at the base of the blade, petiolate or sessile, the petioles rarely myrmecophilous at the apex; exstipulate. Inflorescence axillary and terminal, indeterminate, racemiform or spicate, mostly simple, occa- sionally sparsely branched, mostly elongate and many-flowered, rarely reduced to only a few flowers, erect or nutant; each subtended by a usually tiny and inconspicuous bractlet. Flowers small; calyx tubular or cyathiform, regular or somewhat zygomorphic, thin, accrescent, apically truncate and entire or 5-toothed or -lobed; corolla infundibular or hypocrateriform, mostly yellow or white, varying to blue, violet, or lilac, the tube narrow-cylindric and regular, the limb spreading, usually 5-parted, rarely 4- or 6-parted, with broad, slightly irregular lobes, the 2 hindmost outermost in prefloration, mostly more or less pubescent in the throat; stamens 4, mostly didynamous, inserted at or above the middle of the corolla-tube, included, a fifth stamen represented by a rudimentary staminode, or occasionally stamens 5 or even 6, the filaments very short, the anthers ovate or sagittate, introrse, erect, with 2 parallel thecae opening by longitudinal slits and with a thickened connective which often surpasses the thecae in length; style terminal, included, often thickened upwards, the stigma shortly bifid, ovary perfectly or imperfectly 4-celled, 2-carpellate, each cell with 1 lateral anatropous ovule. Fruit drupaceous, with a juicy exocarp and hard endocarp, the 2 pyrenes 2-celled and 2-seeded, often separated by a median fissure; the fruiting-calyx conspicuously enlarged and indurated, cupuliform or patelliform, shorter than the fruit.
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Habit
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Trees or shrubs
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Distribution
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A genus of 139 species and infraspecific taxa, ranging from Bermuda, Florida, and Texas through Mexico, Central America, and the West Indies to Argentina and Uruguay. Many species are cultivated for ornament in various parts of the Old and New Worlds. Several fossil forms are known from the Tertiary of the United States, Colombia, and Italy.
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Key
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a. Leaves ternate or alternate ...... 1. C. macrochlamys aa. Leaves decussate-opposite or approximate. b. Leaf-blades glabrous or subglabrate beneath when mature. c. Veins and veinlets numerous, the reticulation more or less conspicuous and prom- inulous, at least above when dry ...... 2. C. donnell-smithii cc. Veins and veinlets sparse, the reticulation usually more or less obscure on both leaf-surfaces when dry. d. Leaf-blades mostly blunt, obtuse, or only subacute at the apex; basal pro- longation folded over to enclose a pair of elongate dark glands ...... 3. C. caudatum dd. Leaf-blades distinctly acute or acuminate at the apex, the base not plainly invaginated to enclose the glands. e. Leaf-blades with a basal pair of large, prominent, and conspicuous heavy black glands to 4 mm long ...... 4. C. macradenium ee. Leaf-blades with only a few basal small appressed and inconspicuous glandular disks ...... 5. C. recurvatum bb. Leaf-blades distinctly hairy beneath. f. Flowers sessile or subsessile; leaf pubescence simple. g. Leaf-blades subglabrate, pulverulent, or merely puberulent on the lamina beneath, more or less dichotomously short-pubescent only along the midrib ...... 6. C. viride gg. Leaf-blades velutinous on the entire surface beneath ...... 7. C. cooperi ff. Flowers distinctly pedicellate; leaf-blades densely furfuraceous-tomentose be- neath with many-branched hairs ...... 8. C. lankesteri
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