461 
Chenate mountains) and northern Mexico to California, has a single capitate clus- 
ter appearing somewhat lateral, an involucre of 1 or 2 elongated leaves with | or 2 
bracts, and scales generally brown-margined, 
3. C. polystachys Rottb., var. leptostachys Boeck], Stems very slender, 15 to 
35 em. high: leaves and elongated involucre very narrow: spikelets few to many on 
the 4 to 8 rays, linear, acute 4 to 18 mm. long: scales thin, ovate, acute, closely 
imbricated, pale brown: stamens 2: achene linear-oblong or clavate, short-pointed, 
grayish and minutely pitted. (C. microdontus Torr. C. Texensis Steud,)—Extending 
from the Gulf States into Texas (Sabine Pass). 
* * Umbel compound. 
4. C. Hochstetteri Nees. Stem stout, 3 dm. or more high: involucral leaves 3 to 
5, very long: spikelets linear, spiked and crowded along the branchlets of the sev- 
eral-rayed umbel: scales oval, very obtuse, dark reddish brown, broadly white- 
scarious-margined: stamens 3: achenes broadly ellipsoidal, blackish. (C. flaricomus 
Torr. in Mex. Bound.)—From Louisiana through Texas to New Mexico, 
62. Achene triangular: spikelets usually many-flowered, more or less flattened, with keeled 
scales which are sometimes decurrent upon the rhachis as scarious wings. —E UCYPERUS. 
1* Spikelets oblong to linear, in dense terminal sessile or short-rayed clusters; scales with 
long recurved point, nerved: stamen solitary: achene oblong-obovate, obtuse. 
5, C. aristatus Rottb. Low annual, 2.5 to 12.5 em. high: involuere 2 or3-leaved: 
spikelets chestnut-brown, oblong becoming linear, 7 to 13-flowered, in 1 to 5 ovate 
heads: scales tapering to a long recurved point. (C. inflecus Mubhl.)—In the Chenate 
mountains. Distributed throughout North America, 
2* Spikelets oblong to linear, in simple sessile or unequally-rayed umbellate clusters; 
scales many-nerved (recurved tips in No. 10): stamens 3: achene obovate, sharply tri- 
angular. 
6. C. compressus L. Low annual, 7 to 20 em. high, with a simple sessile or a few 
umbellate clusters of oblong to linear spikelets (15 to 30-flowered and 6 to 16 mm. 
long) with crowded, strongly keeled, many-nerved, and very acute pale scales,— 
Along the Atlantic and Gulf coasts to Texas (Sabine Pass). 
7. C. Rusbyi Britton. Stem slender, about 3 dm. high, from fibrous roots bearing 
short scaly rhizomes: involucre about 5-leaved, equalling the 3 to 5 rays, 1 or 2 of 
which become about 7.5 em. long: heads of 4 to 7 lanceolate acute 13 to 20-flowered 
spikelets with rachises not winged: scales broadly ovate and obtuse, keeled, with 
slightly darker midnerve, about 11-nerved: achene black.—In the Chenate mountains 
(Nealley) and extending to Silver City, New Mexico (Rusby). 
8. C. Buckleyi Britton. Stem quite stout, 5 to 6 dm. high: involucre about 4- 
leaved, mostly elongated: umbel rays 5 to 7, the longest about 10 cm. long: spikelets 
broadly linear, 12 to 20 mm. long, 12 to 20-tlowered, clustered in loose heads of 12 
to 30 at the ends of the rays, the rachis not winged: scales oblong or oblong-ovate, 
obtusish or truncate, with a dark keel and lighter brown somewhat scarious mar- 
gins, 9 to 1l-nerved: achene obtuse, with short point.—Valley of the lower Rio 
wrande; also in Chihuahua and Indian Territory. 
9. C. Schweinitzii Torr. Perennial, propagating from hard clustered corms or 
bulb-like tubers: stems rough on the angles, 3 to6 dm. high: umbel 4 to 8-rayed, 
with very unequal erect rays: spikelets loosely or somewhat remotely 6 to 12-flow- 
ered, with convex many-nerved scales and narrowly winged joints.—From Canada to 
southwest Texas and westward. 
10. C. Fendlerianus Boeck]. Resembling the last species, but distinguished by 
the very short-rayed umbels forming a dense compact cluster, and the strongly 
mucronate scales with horizontal or recurved tips.—On the Rio Grande and west- 
ward to Arizona. 
