360 MISC. PUBLICATION 243, U.S. DEPT. OF AGRICULTURE 
the same species. “Antilles” is probably an error, though possibly 
the species may have been introduced in the slave trade, but failed 
to persist. 
95. CENCHRUS L., Sp. Pl. 1049. 1753 
Spikelets sessile, 1 to several together, permanently enclosed in a 
bristly or spiny involucre or bur, composed of more or less coalesced 
sterile branchlets; burs sessile or nearly so on a slender, compressed, 
or angled axis, its apex produced into a short point beyond the upper- 
most bur, the burs falling entire, the grains germinating within them; 
involucre (especially in our species) somewhat oblique, its body 
irregularly cleft, the lobes rigid, in most species resembling the spines, 
the cleft on the side of the bur next to the axis reaching to the tapering, 
abruptly narrowed or truncate base, the bristles or spines barbed, at 
least toward the summit; spikelets mostly glabrous or nearly so; first 
glume 1-nerved, usually narrow, sometimes wanting; second glume 
and sterile lemma 3- to 5-nerved, the lemma enclosing a well-developed 
palea and usually a staminate flower; fruit usually turgid, mdurate, 
the lemma acuminate, the nerves visible toward the summit, the 
margins thin, flat. Annuals or perennials, with terminal racemes of 
burs. 
Plants perennial. 
Bristles and lobes of the involucre slender and terete or nearly so. 
Burs about 5 mm high; involucral lobes united at base only. 
1. OC. MYOSUROIDES. 
Burs about 7 mm high; involucra!l lobes united a short distance above the 
base. 35s Sac os sped ee Ae evi he ees Denes eee 2. C. EKMANIANUS. 
Bristles unlike, the outer slender, terete, the inner, or the lobes of the involucre, 
flattened at base. 
Lobes of involucre as long as spikelet; thick base of bur nearly as broad as the 
Dur SS eet See es Ae et eee SP oe 7. CC. MICROCEPHALUS. 
Lobes of involucre longer than the spikelets; base of bur triangular, narrower 
than the bur. 
Blades involute, squarrose, conspicuously distichous, not more than 2.5 cm 
long about 16m apart. ono ee eee 3. C. DISTICHOPHYLLUS. 
Blades not involute and squarrose, nor conspicuously distichous, much 
longer. and furtherapaniie 2-3-2 42. eeeee 6. C. GRACILLIMUS. 
Plants annual. 
Involucre with a ring of slender bristles at base. 
Burs, excluding the bristles, not more than 4 mm wide, numerous, crowded 
in a long spike; lobes of involucre interlocking, not spinelike. 
. CC. BROWNII. 
Burs, excluding bristles, about 5.5 mm wide, not densely crowded; lobes of 
the involucre erect or nearly so or rarely one or two lobes loosely inter- 
locking. ‘the tips spinelike:? -eneres. Fgbee t Seeeee nae 5. C. ECHINATUS. 
Involucre with flattened spreading spines, no ring of slender bristles at base. 
Burs, including spines, 7 to 8 mm wide, finely pubescent. 
8. C. PAUCIFLORUS. 
Burs, including spines, 10 to 12 mm wide, usually densely woolly. 
9. C. TRIBULOIDES. 
1. Cenchrus myosuroides H.B.K., Nov. Gen. et Sp.1:115. pl. 35. 
1815. Cuba. Flamingo Key (near Bataban6é), Humboldt and 
Bonpland. 
Pennisetum myosuroides Spreng., Syst. Veg. 1: 303. 1825. 
Cenchropsis myosuroides Nash, in Small, Fl. Southeast. U.S. 109, 
13272 Ss: 
Plants perennial; culms solitary or in small clumps, usually 1 to 
2 m tall, glabrous, rather robust and woody, commonly glaucous, 
