Culms (9)20–130 cm. Sheaths glabrous or hairy, sometimes scabridulous; ligules (1)1.5–2.5 mm, erose-ciliate, more or less lacerate; blades 5–14 cm long, (1)2–8 mm wide, usually flat, rarely slightly involute, scab-rous or pubescent. Panicles (2)5–15(25) cm long, 0.5–2 cm wide, usually erect, often spikelike, spikelets usually densely arranged. Spikelets 2.2–3.6 mm. Lower glumes less than 1/3 as wide as the upper glumes; upper glumes 1.5–2.5 mm, subcucullate, width/length ratio 0.3–0.5, apices rounded to truncate; lowest lemmas 1.9–2.8 mm, usually scabridulous distally; distal lemmasusually smooth on the sides, occasionally scabrous, unawned; anthers 0.2–1 mm. 2n = 14.

Sphenopholis obtusata grows in prairies, marshes, dunes, forests, and waste places, at 0–2500 m. Its range extends from British Columbia to New Brunswick, through most of the United States, to southern Mexico and the Caribbean. The distal lemmas of S. obtusata are occasionally somewhat scabrous. Such plants can be distinguished from S. nitida by their narrower lower glumes, from S. filiformis by their wider leaves, and from S. pensylvanica by their shorter, unawned spikelets. Hybrids with S. pensylvanica, called Sphenopholis ×pallens, have short (0.1–4 mm) awns on the distal lemmas.