Plants annual. Culms 1-3 m, erect, or geniculate and ascending. Sheaths glabrous, not flattened at the base. False panicles 20-100 cm; sheaths subtending the rame clusters 35-40 mm, pilose, hairs papillose-based; rames 3-5 per cluster, with 2-3 heterogamous spikelets. Homogamous spikelets 8-10 mm; lower glumes glabrous, acuminate. Heterogamous sessile spikelets 9-11 mm; calluses 3-4 mm; lower glumes hispid and tuberculate-scabrous, dark brown; awns 7-9 cm; pedicellate spikelets 8-10 mm. 2n = 20.

Themeda arguens is native to northern Australia and southeastern Asia. Reed (1964) reported finding it on ore piles in Maryland and Virginia.