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Project Name Data (Last Modified On 10/23/2012)
 

Flora Data (Last Modified On 10/23/2012)
Genus CYPERUS L.
PlaceOfPublication Sp. P1. 44. 1753
Reference Kuekenthal, Pflanzenr. IV20:1-671. 1936.
Description Annuals or perennials, the culms simple, usually triangular and leafy; inflores- cence involucrate in dense spikes or in clusters, capitate or on rays which are often compound; spikelets flat or subterete, few- or many-flowered, the rachis often winged, the scales concave, 2-ranked; flowers perfect; perianth none; stamens 1-3; style 2- to 3-cleft; achene lenticular or 3-angulate.
Note About 600 species, chiefly in tropical regions.
Key a. Style 2-cleft. b. Surface of achene with vertically elongated cells. c. Cell margins whitened in age; scales 2 mm. long, yellow to light brown _ - - - -------- ---_ 1. C. FLAVESCENS cc. Cell margins not whitened in age; scales 1 mm. long, deep brown- 2. C. PICEUS bb. Surface of achene with quadrate cells, frequently with embossed or papillose centers. c. Spikelets 4-5 mm. wide - _ - _ --3. C. UNIOLOIDES cc. Spikelets 1-3 mm. wide. d. Spikelets greenish to yellowish-brown. e. Spikelets 1-1.5 mm. wide; dwarf annuals rarely taller than 10 cm. ------ - - - - - - - --- 5. C. POLYSTACHYUS ee. Spikelets 2-3 mm. wide; the scale margins strongly hyaline 4. C. ALBOMARGINATUS dd. Spikelets black to shining chestnut-brown; 2-3 mm. wide; the scale margins not strongly hyaline - _ -- 6. C. NIGER aa. Style 3-cleft. b. Culm terete, naked, usually over a meter high - _ _ - 15. C. GIGANTEUS bb. Culm more or less trigonous, leafy at least below. c. Decurrent scale bases (i.e. wings of the rachilla) becoming corky at maturity; the rachilla breaking into 1-fruited j - s 7. C. FERAX cc. Rachilla wings not becoming inflated and corky. d. Inflorescence of dense, rigid, cylindric spikes. e. Spikes usually sessile in a capitate inflorescence --.12. C. FLAVUS ee. Spikes digitately compound on long rays l- - 0. C. LIGULARIS dd. Inflorescence not of dense cylindric spikes. e. Spikes loosely cylindric, the spikelets readily falling at maturity. f. Scales with a long awn - - - _ - _ - _ 8. C. PANAMENSIS ff. Scales not awned. g. Spikes broader at base; achene oblong-elliptic ---13. C. HERMAPHRODITUS gg. Spikes not broader at base; achene linear-oblong -- 9. C. TENUIS ee. Inflorescence of globose heads or of flattened racemes. f. Spikelets small (2-5 mm. long), flattened, in dense glom- erulate clusters, mostly on short compound rays. g. Achenes yellowish-brown, 1 mm. long -----21. C. LUZULAE gg. Achenes brick-red, rough, 0.7 mm. long --- 22. C. SURINAMENSIS ff. Spikelets not glomerulate on compound rays. g. Spikelets quadrangular, in loose globular heads - 11. C. GLOBULOSUS gg. Spikelets flattened, in umbellate or racemose clusters. h. Ultimate clusters of spikelets forming simple umbels. i. Umbels sessile. j. Spikelets green--- - 17. C. COMPRESSUS jj. Spikelets white - -- - 20. C. TENERRIMUS ii. Umbels on rays. j. Rays short (up to 5 cm.). k. Spikelets brown - - __ - 24. C. HASPAN kk. Spikelets green --- - 17. C. COMPRESSUS jj. Rays long (mostly 10-20 cm.). k. Culrms shorter than the rays; stamen I - 23. C. SIMPLEX kk. Culms longer than the rays; stamens 2 or 3 25. C. DIFFUSUS hh. Ultimate clusters of spikelets racemose (i.e. axis of the cluster more or less elongate); inflorescence with prominent rays. i. Clusters narrow (4 to 5 times longer than broad); inflorescence elongate _ - -14. C. PROLIXUS ii. Clusters only slightly longer than broad; inflorescence not elongate. j. Spikelets purple to dark brown - -- 16. C. ROTUNDUS ij. Spikelets green, yellow, or yellow-brown. k. Spikelets dull green; rachilla not winged - 19. C. SPHACELATUS kk. Spikelets yellow to yellow-brown; achenes partly enclosed by the winged rachis - .18. C. ESCULENTUS
 
 
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