466 
38. C. cylindricus Britton. Like the last, but heads cylindrical or oblong, spike- 
lets usually 2-flowered, and achene linear-oblong. (C. Torreyi Britt., not C. cylindricua 
Chapman. )—From the north Atlantic and Gulf States to southwestern Texas, 
39. C. retrofractus Gray. Stem and leaves usually minutely downy, 3 to 9 dm. 
high: spikelets slender, awl-shaped, very numerous in obovate or oblong heads ter- 
minating the elongated rays, soon strongly reflexed, 1 or 2-flowered in the middle: 
the empty scales ovate, the fertile lanceolate and pointed, the uppermost involute- 
awl-shaped: achene linear.—From the south Atlantic and Gulf States to Texas. 
40. C. flavomariscus Griseb. Stems usually slender, from creeping-rootstocks, 3 
to 6 dm. high, exceeding the leaves: spikes about 5 (4 to 6), very dense: spikelets 
spreading, oblong-lanceolate, acute, 2-flowered, 1-fruited: scales yellowish or brown- 
ish, ovate, about 1l-nerved: achene triangular-obovate.—Valley of the lower Rio 
Grande and southward. 
41. C. uniflorus Torr. & Hook. Stem filiform, triangular, smooth (3 dm. or 
more high), longer than the very narrow leaves: involucre of 3 leaves much longer 
than the simple 4 or 5-rayed umbel: spikes of about 25 spikelets irregularly spreading 
in ali directions: spikelets approximated, subulate, 2 or 3-flowered (only the lower 
floret fertile): scales linear-lanceolate, slightly mucronate: stamens 4: achene 
oblong-linear, partly embedded in the broad rachis and covered with the inflexed 
margin.—Texas (Drummond). Var. PUMILUs Britton, of the lower Rio Grande, is 
about 7.5 cm. high, with a single (occasionally slightly compound) head of 8 to 20 
spikelets mostly composed of 3 glumes (lowest persistent and empty, middle one 
fertile, uppermost sterile and subulate). 
** Spikelets 4 to 12-flowered. 
42. C. filiculmis Vahl. Perennial, propagating from hard clustered corms or bulb- 
like tubers: stem slender, wiry, often reclined, 2 to 4 dm. high: leaves linear or fili- 
form: spikelets numerous and clustered in one sessile dense head, or in 1 to 7 addi- 
tional looser heads on spreading rays of an irregular umbel: scales many-nerved, 
blunt, greenish: stamens 3: achene obovate, sharply triangular.—Extending from 
the northern States into Texas. 
43. C. echinatus Britton. Annual, with fibrous roots: stem 3 to 6 dm. high, 
longer than the linear leaves: umbel 6 to 12-rayed: heads globose or oblong: spike- 
lets linear, acute: scales greenish or yellowish, oblong, obtuse, mucronate: achene 
oblong. (C. Baldwinit Torr.)—From North Carolina and Florida to the lower Rio 
Grande. 
2. KYLLINGA Rottboell. 
Stems leafy at base, with 3-leaved involucre, spikes densely aggre- 
gated in solitary or triple sessile heads, one-flowered spikelets of 3 or 4 
two-ranked seales (the 2 lower scales minute and empty), and lenticular 
achene. 
1. K. pumila Michx. Annual: stems 5 to 25 em. high: leaves linear: head glob- 
ular or 3-lobed, whitish-green: spikelets strictly 1-flowered: upper scales ovate, 
pointed, rough on the keel: stamens and styles 2.—Extending from the Mississippi 
Valley States into Texas. 
3. DULICHIUM Pers. 
A perennial herb, with terete simple hollow stem jointed and leafy 
to the summit, 6 to 10-flowered linear flattened spikelets sessile in 2 
ranks on axillary solitary peduncles emerging from the leaf-sheaths, 
2-ranked lanceolate scales which are decurrent and form flat wing-like 
