Plants annual. Culms 20-100 cm, ascending from a geniculate base.
Sheaths from shorter than to equaling the internodes, compressed; ligules
0.7-1.7 mm; blades 4-18(35) cm long, 2-10(14.2) mm wide, adaxial surfaces
sparsely pilose, hairs papillose-based. Panicles 2.5-12 cm; rachis internodes
2-4 mm; fascicles 5-10 mm long, 3.5-6(6.3) mm wide, imbricate; outer
bristles 10-20, terete, the majority no more than 1/2 as long as the inner
bristles; inner bristles 2-5 mm long, 0.6-1.5 mm wide, flattened, not grooved,
mostly erect, fused for at least 1/2 their length into a globose cupule, sometimes
interlocking at maturity, shortly pubescent, often purple at maturity. Spikelets
2-3(4) per fascicle, 4.8-7 mm. Lower glumes 1.3-3.4 mm; upper glumes
3.8-5.7 mm, 3-7-veined; lower lemmas 4.5-6.5 mm; upper florets 4.7-7
mm; anthers 0.8-2.4 mm. Caryopses ovoid, 1.2-3.2 mm long, 1.3-2.2
mm wide. 2n = (34), 68.
Cenchrus echinatus grows in disturbed areas throughout the coastal plain
and piedmont of the southern United States, Mexico, Central and South America,
and, as an unwelcome introduction, elsewhere.
Annual, ascending from a geniculate base, 2-8 dm; lvs 4-25 cm נ4-10 mm; burs well spaced on a flexuous rachis, short-hairy, 5-10 נ3.5-6 mm, truncate at the base, the single row of coarse upper spines 2-5 mm, retrorsely scabrid, mostly erect, sometimes interlocking, those of the outer rows finer, half as long, more divergent or some of them reflexed; spikelets 2-3 per bur, 5-7.5 mm; 2n=34, 68. Sandy waste places and forest-margins; trop. Amer., n. to N.C. and even D.C.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.