Plants perennial. Culms to 90 cm, mostly decumbent and rooting at the nodes, distal 15-35 cm ascending when flowering; nodes usually pubescent; internodes usually pubescent along 1 side (sometimes glabrous). Sheaths conspicuously ciliate on the margins; ligules 0.4-1.6(2.3) mm, ciliate; blades (0.6)1.3-11.5 cm long, 2-20 mm wide, glabrous, scabrous, or pubescent, margin(s) usually undu-lating. Panicles (1.5)2.5-16.5 cm, with 2-10 primary branches; branches 0.1-2.5 cm. Spikelets 2.2-3.5(4.5) mm; calluses shortly pubescent at the base awns usually purplish. Lower glumes 1.5-3 mm, scabridulous and/or pubescent, 3-5-veined, awns (1.6)3.2-14.5 mm; upper glumes 1.5-2.5 mm, sparsely pubescent, 5-7-veined, awns 0.8-6(10) mm; lower florets usually sterile, occasionally staminate; lower lemmas 2.2-3.1 mm, sparsely pubescent above, (5)7-9-veined, awns 0.1-1.2 mm; lower paleas absent or to 2.3 mm, hyaline; upper lemmas (2.1)2.3-3 mm, glabrous, weakly cartilaginous, white to cream-colored; anthers 3, 1.3-1.7 mm. Caryopses 1.7-1.8 mm long, 0.5-0.9 mm wide, glabrous. 2n = 36, (54), 72, (90).
Md., Okla., Miss., Ala., N.C., La., Puerto Rico, Virgin Islands, Va., S.C., Ark., Fla., Ga., Pacific Islands (Hawaii), Mo., Tex.
Oplismenus hirtellus grows at scattered locations in the southeastern United States, extending south in subtropical and tropical habitats to Argentina. Scholz (1981) recognized 11 subspecies and two forms within the species, but they overlap, both morphologically and geographically. The key below is included for convenience. It includes the three subspecies attributed to the Flora region. In addition, a variegated form culti
|1||Sheaths and culms noticeably pilose, the hairs 1-3 mm long; lemmas 7-veined||Oplismenus hirtellus subsp. undulatifolius|
|1||Sheaths and culms glabrous or with a few, scattered hairs less than 1 mm long; lemmas (7)9-11-veined.||> 2|
|2||Spikelets 2.2-2.7(3.3) mm long; lowest panicle branches 0.1-0.5 cm long||Oplismenus hirtellus subsp. setarius|
|2||Spikelets 3-3.4(4.5) mm long; lowest panicle branches 0.5-0.7 cm long||Oplismenus hirtellus subsp. fasciculatus|