Cenchrus tribuloides L.

Stout, much branched, decumbent or trailing annual 2–10 dm; sheaths villous at the summit and ± villous-ciliate; blades 2–14 cm × 3–14 mm; burs densely villous, 9–16 × 4–8 mm (spines excluded), with mostly 15–40 basally flattened, distally retrorse-barbed spines 4–8 mm; spikelets 6–9 mm, 1(2) per bur and concealed in it; 2n=34. Coastal sands, especially on dunes; s. N.Y. to Fla. and Tex., and rarely in trop. Amer.