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(Last Modified On 4/10/2013)
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(Last Modified On 4/10/2013)
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Genus
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Prestonia R. Br.
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PlaceOfPublication
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Mem. Wern. Nat. Hist. Soc. 1: 69. 1811.
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Description
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Lianas, suffruticose to slightly herbaceous, lacticiferous. Leaves opposite, non- glandular, pinnately-nerved; petioles somewhat perfoliate, mostly glandular in the axils. Inflorescences ? corymbose, racemose, or umbellate, mostly axillary, rarely subterminal. Flowers mostly medium-sized to large; calyx 5-lobed, the lobes equal to subequal, bearing 1 or rarely several squamellae within; corolla salverform to subinfundibuliform, with or rarely without 5-epistaminal append- ages, the orifice with a thickened annulus, the tube straight or gibbous, the limb 5-lobed, dextrorsely convolute; stamens 5, included or half exserted, the anthers connivent and agglutinated to the stigma, with an enlarged connective; gynoeci- um 2-carpellate, apocarpous, the ovary superior, the ovules many, the nectaries 5, separate or concrescent, thin or fleshy, the style 1, the stigma fusiform or sub- capitate, sometimes weakly umbraculiform below. Fruit ? apocarpous, sometimes connate apically or ? agglutinated, of (1-)2 follicles; seeds many, dry, comose apically.
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Habit
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Lianas
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Distribution
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A large genus of about 60 species mostly in northern South America, but found also in Mexico, Central America, the West Indies, and as far south as Argentina.
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Reference
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Woodson, R. E., Jr. Prestonia. Pp. 276-367 in "The American genera of Echitoideae." Ann. Missouri Bot. Gard. 23: 169-438. 1936.
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Key
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a. Calyx-lobes small and inconspicuous, ca. 1.5-2 mm long, ? reflexed.... 1. P. acutifolia aa. Calyx-lobes large and conspicuous, ca. 4-25 mm long, ? erect. b. Corolla glabrous or only papillate externally. c. Nectaries separate, or connate only basally; calyx-lobes cc. Nectaries concrescent; calyx lobes mostly > 10 mm long. d. Nectaries thick and fleshy throughout, shorter than the ovary ........... 3. P. obovata cc. Nectaries thin and ? diaphanous, at least on the margins, surpassing the ovary at anthesis ............................. 4. P. portobellensis bb. Corolla densely pubescent externally at least on the lobes. e. Corolla-tube with elongate epistaminal appendages within; calyx-lobes 9-11 mm long ..................................... 5. P. ipomaeifolia ee. Corolla-tube without elongate epistaminal appendages within; calyx-lobes mostly > 11 mm long. f. Each calyx-lobe with a single deltoid squamella. g. Annulus distinctly 5-lobed .......... ................. 6. P. allenii gg. Annulus ridged and uneven, but not distinctly 5-lobed .... 7. P. wedelii ff. Each calyx-lobe bearing several thin calycine squamellae ... 8. P. remediorum
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