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(Last Modified On 10/23/2012)
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(Last Modified On 10/23/2012)
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Genus
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RYNCHOSPORA Vahl
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PlaceOfPublication
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Enum. 2:229. 1806.
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Description
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Plants mostly perennial, sometimes annual, the culms 3-angulate or terete; spikelets oblong or fusiform, variously arranged, the scales 1-nerved, spirally imbricate; upper flowers staminate, the lower perfect; perianth of bristles, or sometimes wanting; stamens usually 3; style 2-cleft or rarely entire; achene lenticular or turgid, smooth or transversely rugose, capped by the persistent style base.
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Distribution
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About 200 species, widely distributed, especially in warm regions.
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Key
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a. Spikelets all crowded in a single dense head. b. Bracts 10-30 cm. long; leaves 8-15 mm. wide - - _ - 1. R. CEPHALOTES bb. Bracts 4 cm. long or less; leaves 3 mm. wide or narrower. c. Plants glabrous; bracts not ciliate - -----2. R. GLOBOSA cc. Plants pubescent; bracts ciliate. d. Bracts partly leaf-like; outer spikelets reflexed or spreading - 3. R. BARBATA dd. Bracts all thin and scarious; spikelets all erect --- 4. R. ARMERIOIDES aa. Spikelets variously arranged but never in a single head. b. Branches of the style equaling or longer than the undivided portion. c. Spikelets 1-1.5 mm. long - _ - --5. R. MICRANTHA cc. Spikelets 3-10 mm. long. d. Achenes reticulate - - _ - _ - 6. R. HIRSUTA dd. Achenes transversely rugose. e. Spikelets in congested heads; dwarf annual plants; achene 1 mm. long, tridentate at the apex - ------ 7. R. SETACEA ee. Spikelets in wide-spreading corymbs. f. Base of the style depressed, almost discoid; scales very acute - - _ - _ - _ - 8. R. EXIMIA ff. Base of the style pyramidal; scales obtuse - - 9. R. ROBUSTA bb. Branches of the style short or none, much shorter than the un- divided portion. c. Spikelets in globose heads ---------- - -10. R. CYPEROIDES cc. Spikelets not in globose heads. d. Spikelets fasciculate, in 2's-6's, yellow or yellow-brown. e. Inflorescence elongate, of several corymbs - -- 11. R. CORYMBOSA ee. Inflorescence a single corymb --- 12. R. AMAZONICA dd. Spikelets mostly solitary, greenish or chestnut-brown. e. Inflorescence much shorter than the basal leaves; leaves silvery - - _ _ __ - ___ - - 13. R. ARGENTEA ee. Inflorescence much surpassing the basal leaves; leaves green. f. Bristles obsolete or nearly so; spikelets stramineous; in- florescence-branches elongate ----- 14. R. POLYPHYLLA ff. Bristles equaling or longer than the achenes; spikelets greenish to dark brown; inflorescence-branches broadly triangular. g. Spikelets 3-4 mm. long -15. R. LOCUPLES gg. Spikelets dark brown, 7-9 mm. long.- 16. R. MACROCHAETA
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