Plants annual, usually slender. Culms (15)25-45(65) cm tall; nodes hairy; internodes grooved, usually hairy in the grooves, less so than over the nodes. Leaves light green; sheaths glabrous or sparsely hairy, the edges ciliate; ligules 0.6-1.2(1.8) mm, ciliate; blades (2)3-7(8) cm long, 6-13 (16) mm wide, ovate-oblong to oblong-lanceolate, usually hairy , midvein weak, with 2-3 lateral veins on each side, cross venation usually visible. Panicles (3)4-8(10) cm, sometimes hairy, with 3-10 primary branches; lower primary branches (0.2)0.5-1.5(3) cm long, with (3)10-20(25) spikelets, spikelets borne in pairs, usually encircled at the base with hairs almost as long as the spikelets. Spikelets (2)2.8-3.5 mm long, usually densely hairy, sometimes glabrous, flattened to rounded on the back. Lower glumes (1.3)1.9-2.4 mm, 0.7-0.9(1.2) mm wide, oblong-oval, densely hairy, with 3-5(7) veins, awned, awns (3)6-11(15) mm long, frail, whitish, and scabrous; upper glumes (1.5)2-2.3 mm long, (0.7)-1.2(1.5) mm wide, similar to the lower glumes in shape, fairly densely hairy, with 5-7 veins, awned, awns (0.4)3-6(9) mm long, frail, whitish, and scabrous; lower lemmas (2)-2.6-3.5 mm long, (1)1.7-2.4 m wide, oblong, with (5)7-9(11) veins, pointed or shortly awned; lower paleas absent. Caryopsis oblong-lanceolate.

Oplismenus burmannii is a pan-tropical species that is most abundant in Africa. It was discovered in Florida in 2006 (Davis et al. 2006). It was treated by Scholz (1981) as O. hirtellus subsp. affinis. Davis et al. (2006) cite McVaugh (1983) in support of its recognition as a species.