CYPERACEAE 167 



18. Cypsrus Buckley! Britton. Perennial, bright green. Leaves several at the 

 base of the scape ; blades 2-7 mm. wide, curling in age : scapes sometimes tufted, 3-15 dm. 

 tall, overtopping the leaves, often conspicuously elongated : bracts of the involucre usually 

 3-5, 10-20 cm. long or the smaller ones shorter : umbel of 3-8 rays varying from 1-12 cm. 

 in length and one or more spikes sessile in the involucre : spikelets linear, 8-12 mm. long, 

 rather lax : scales light or dark chestnut, rhombic-ovate, 3 mm. long, obtuse, with several 

 prominent ribs, not crowded, spreading and deciduous in age : achenes 3-angled, obovoid, 



2 mm. long, brown. 



In river valleys, the Indian Territory and Texas to adjacent Mexico. Summer and fall. 



19. Cyperus Bushii Britton. Perennial by tuber-like corms. Leaves shorter than 

 the scape, 4 mm. wide or less, smooth, not viscid : scapes slender, smooth, 3-6 dm. tall : 

 bracts of the involucre 3-5, the longer much exceeding the umbel : umbel simple, 1-5-rayed, 

 the rays mostly short, or spikes congested into a single cluster : spikelets loosely capitate, 

 linear, compressed, acute, 8-16 mm. long, 11-15-flowered : scales firm, shining, oblong, 

 mucronate, strongly about 11-nerved : stigmas 3 : achene oblong, about 2 mm. long, nearly 

 twice as long as thick, 3-angled, pale brown, apiculate, as long as the scale. 



In sandy soil, Minnesota and Wisconsin to Nebraska and the Indian Territory. Summer. 



20. Cyperus elegans L. Perennial, pale green. Leaves several at the base of the 

 scape, viscid ; blades mostly 2-4 mm. broad, involute above the loose, striate sheaths : 

 scapes tufted, 2-7 dm. tall, sometimes equalled by the leaves or overtopped by them : 

 bracts of the involucre 3-5, very unequal, some 5 cm. long, others often 30 cm. long : 

 umbel simple or compound, usually of 3-6 rays, 1-8 cm. long, with one or more spikes ses- 

 sile in the involucre : spikelets linear-oblong, 6-12 mm. long, crowded : scales light tan- 

 colored, rhombic-ovate, 3 mm. long, ascending, scabrous on the back, with more or less 

 spreading short awn-like tips : achenes 3-angled, obovoid, fully 1.5 mm. long including the 

 curved subulate beak. 



In sandy soil, Florida to Texas and New Mexico. Also in tropical America. Spring to fall. 



21. Cyperus aciiminatus Torr. & Hook. Annual. Leaves light green ; blades 

 usually less than 2 mm. wide : scapes very slender, tufted, 7-40 cm. tall : bracts of the in- 

 volucre much elongated : umbel 1-4-rayed, simple, rays short : spikelets flat, ovate-oblong, 

 obtuse, 4-8 mm. long, many-flowered, densely capitate : scales oblong, pale green, 3-nerved, 

 coarsely cellular, conduplicate, each with a short sharp more or less recurved tip : stigmas 



3 : achenes sharply 3-angled, gray, broadly oblong, narrowed at each end, little over 0.5 

 mm. long, about as long as the scales. 



In moist soil, Illinois to Iowa, Oregon, Louisiana, Texas and California. Summer and fall. 



22. Cyperus cyrtdlepis Torr. & Hook. Perennial, bright green. Leaves mostly 

 overtopped by the scape ; blades 3-4 mm. long, more or less revolute : scapes usually tufted, 

 slender, 1-5 dm. long, smooth : bracts of the involucre 3-5, the longer ones surpassing the 

 umbel, spreading : umbel capitate, or of 3-6 rays and some spikes sessile in the involucre, 

 often compound : spikelets oblong or ovate-oblong, 5-7 mm. long, gray or yellowish, 16- 

 24-flowered : scales ovate, barely 2 mm. long, acute, scarious-margined, with short re- 

 curved spreading tips : achenes 3-angled, elliptic or narrowly oblong, about 1 mm. long, 

 acute or slightly pinched at both ends, rather lustrous. 



In swampy grounds, Arkansas to Arizona and Texas. Spring to fall. 



23. Cyperus Drummdndii Torr. & Hook. Perennial. Leaves much shorter than 

 the scape ; blades 4-6 mm. wide : scapes 8-12 dm. tall, its angles very sharp, or almost 

 winged, scabrous : bracts of the involucre usually 2, surpassing the umbel : umbel capitate 

 or congested, or with several more or less elongated rays, of many (40-50) spikelets : spike- 

 lets lanceolate to oblong-lanceolate, 20-30-flowered, 6-12 mm. long, yellowish : scales lan- 

 ceolate, very closely imbricated, acute : achenes 3-angled, linear-oblong, above the slender 

 stipe. 



On plains or prairies, Texas. Summer. 



24. Cyperus ochrkceus Vahl. Perennial, bright or yellowish green. Leaves over- 

 topped by the scape ; blades mostly 2-6 mm. long, smooth : scapes solitary or tufted, rela- 

 tively slender, 2-12 dm. tall, smooth : bracts of the involucres mostly 3-5, the longer ones 

 much surpassing the umbel, spreading : umbel mostly compound, of 5-10 rays of various 

 lengths, rarely over 15 cm. long, and one or more spikes sessile in the involucre : spikelets 

 linear-oblong to linear-lanceolate, 5-12 mm. long, 25-35-flowered : scales ovate, 2 mm. long, 

 rather blunt : achenes ovoid, slightly pinched at both ends, not stipitate. 



In sandy soil, Alabama to Texas. Also in the West Indies and Mexico. Spring to fall. 



25. Cyperus virens Michx. Perennial, pale green. Leaves elongated ; blades 6-12 

 mm. wide, striate : scapes stout, often tufted, 5-15 dm. tall, overtopping the leaves, smooth, 

 naked above : bracts of the involucre 3-7, variable in length, the longer surpassing the 



