462 
3” Spikelets lanceolate and flat, in rather lax subglobose clusters in single umbels: scal 
acuminate: stamens 3: achene attenuate at base. 
11. C. viscosus Ait. Stem stout: involucre 3 or 4-leaved, very long: umbe 
simple, with 3 to 6 very uneqal rays: spikelets 10 to 14-flowered: scales somewh: 
remote, ovate, subrecurved mucronate at apex, the keel denticulate-spinulose abov: 
achene black. (C. trachynotus Torr.)—Extending from the Gulf States into Tex: 
(ravines near the mouth of the Pecos, etc.) and southward. 
4” Spikelets in dense globose heads in mostly compound umbels: scales acute, 3-nerv 
(sometimes nerveless): stamen mostly solitary: achene linear to oblong, mostly acu 
or acuminate at each end. 
12. C. pseudovegetus Steud. ‘Tall perennial, 3 to 12 dm. high: leaves and invo 
ucre very long and keeled: umbel compound, many-rayed: spikelets ovate, 3 m1 
long, innumerous small greenish heads: scales narrow, pointless (acutish), obscure! 
3-nerved: achene pale, linear, on a slender stipe. (C. virens Gray, in part, n 
Michx. ©. Luzula, var. umbellatus Britton. C. calearatus Wats. & Coult. )—Exten: 
ing from the Atlantic and Gulf States to Indian Territory and Texas (Sabine Pass 
13. C. virens Michx. Tall stout perennial, 3 to 12 dm. high: leaves and inv: 
lucre very long, broad and strongly keeled: umbels compound, often muc 
reduced: spikelets ovate-oblong, acute, 4 to 8 mm, long: scales green, acutis. 
obscurely 3-nerved: achene oblong, acute at each end, brown, 1 mm. long.—Fro 
the South Atlantic and Gulf States to Texas, Mexico, and California. 
14. C. Surinamensis RKotth. An annual, with stems 15 to 40 em. high, ver 
rough, and longer than the narrow leaves: umbels compound, of 4 to 6 prima 
rays, and as many smaller ones, shorter than the 4-leaved involucre: spikelets oblox 
or oblong-linear, 40 to 50-flowered, 10 to 20 in a head: scales yellowish, ovat 
acute, 3-nerved: achene oblong, pointed, abruptly contracted at base, minute 
wrinkled. (C. Drummondii Torr.)—From the Gulf States through eastern Texas + 
Mexico. 
15, C. ochraceus Vahl. Stems 2 to 6 dm. high, smooth, about as long as tk 
leaves: involucre of about six very long leaves and several short ones: umbel mo: 
or less compound, with many unequal rays from almost sessile to 5 to 10 em. long 
spikelets linear, obtuse: scale ovate, mucronate, loosely spreading, yellowish-brow1 
stamens 3: achene oblong, acute, sharply triangular.—From western Louisiar 
through eastern Texas to Mexico. 
16, C. reflexus Vahl. Stem (4.5 dm. high) smooth, longer than the rather rigi 
very narrow flat leaves: involucre of about three elongated leaves: spikelets ovat 
oblong or linear-oblong, 11 to 30-flowered, crowded in subglobose heads in simp. 
or somewhat compound 4 to 5-rayed umbels: scales ovate, carinate, acute, | 
nerved (keel green, sides reddish-brown), closely imbricated and straight: stamer 
1 to 3: achene elliptical, acuminate at each end. (C. rufescens Torr, & Hook.)- 
Eastern Texas. 
17. C. cyrtolepis Torr. & Hook. Stems cespitose, slender and wiry, 3 dm. « 
more high: leaves very slender, nearly as long as the stem: involucre of 3 or 4 set: 
ceous leaves: heads in a3 to 5-rayed umbel (rays very unequal and erect): spikele 
broadly ovate, 9 to 12-flowered, the florets distant: scales lanceolate, acute, recurve 
and spreading, nerveless, dull greenish-white (or yellowish): achene oblong, acut 
at each end, smooth and dull.—From Sabine Pass to Arizona, Var. DENTICARINATL 
Britton (C. rufescens, var. denticarinatus Britton), from the valley of the lower R: 
Grande, has scales with a prominent keel which is armed with small hyaline teet 
near its apex, and umbel appearing somewhat lateral. 
18. C. acuminatus Torr. & Hook. Slender, 7.5 to 30 cm. high: involucre 2 « 
3-leaved: spikelets short, ovate, becoming oblong, 16 to 30-flowered, pale: scal 
obscurely 3-nerved, short-tipped: achene oblong, pointed at both ends.—A Missi 
sippi Valley species, extending to Louisiana, Texas, and Arizona. 
