Cenchrus longispinus (Hack.) Fernald
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Spreading or ascending annual 2–8 dm, usually branched; sheaths villous-ciliate distally; blades 6–18 cm × 3–7 mm; burs hairy, 8–12 × 3.5–6 mm (spines excluded), with numerous (mostly 45–75) retrorsely barbed, slender spines 3.5–7 mm, the lower spines relatively short and pointed downward; spikelets 2–3(4) per bur, 6–8 mm, exserted at the tip, visible down to the middle through the lateral cleft in the bur; 2n=34. A weed in sandy soil or disturbed habitats; Me. to Fla., w. to N.D., Oreg., Calif. and Tex.