CYPERACEAE 167 
18. Cyperus Buckleyi 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 Büshii 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, 4 as long as the scale. 
In sandy soil, Minnesota and Wisconsin to Nebraska and the Indian Territory. Summer. 
20. Cyperus élegans 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 em. 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 acuminàtus 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 à as long as the scales. 
In moist soil, Illinois to Iowa, Oregon, Louisiana, Texas and California. Summer and fall. 
22. Cyperus cyrtólepis 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 Drummóndii 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- 
OA very closely imbricated, acute: achenes 3-angled, linear-oblong, above the slender 
stipe. 
On plains or prairies, Texas. Summer. 
24. Cyperus ochraceus 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 vírens 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 
