Culms to 70 cm. Sheaths smooth or retrorsely scabrid-ulous, usually glabrous, some-times pubescent; ligules 0.7–2.6 mm, glabrous, erose; blades 8–18 cm long, 2–10 mm wide, flat. Panicles 15–20 cm long, 1.5–2.5 cm wide, nodding, not spikelike, spikelets loosely arranged. Spikelets 4–5.2 mm. Lower glumes about 1/3 as wide as the upper glumes; upper glumes 3–3.9 mm, elliptical to oblanceolate, not subcucullate, width/length ratio 0.17–0.26, apices acute; lowestlemmas 3.1–4.2 mm, glabrous; distallemmas usually smooth on the sides, rarely scabridulous distally, unawned; anthers0.2–0.7 mm. 2n = 14.
Sphenopholis longiflora grows in forest bottoms along bayous and streams, from 0–50 m, in Texas, Arkansas, and Louisiana. Erdman (1965) treated both S. longiflora and S. intermedia as S. obtusata var. major (Torr.) Erdman. They are morphologically distinct from each other, and from S. obtusata.