A tufted perennial 200-1500 mm high, stoloniferous, sometimes rooting and branching from lower nodes; basal sheaths glabrous to densely hairy, usually not splitting into fibres. Leaf blade 20-300 x 3-20 mm. Racemes (2-)3-15, 20-80 mm long (Gibbs Russell et al. 1990). Spikelet 3-5 mm long, ovate; lower glume (the bracts at the base of the spikelet) 2 / 3 - 5 / 6 as long as spikelet, 3-nerved, with 1-3 stiff hairs on the back, apex broadly rounded; upper glume 5-nerved, usually without cross-veins, glabrous or pubescent; lower lemma (encloses grass flower) with or without a fringe of stiff hairs near the margins; upper lemma with well developed awn 0.5-1.2 mm long; anther 1.0-2.0 mm long.

Flowering October to May.

Two closely related species are: U. stolonifera, a smaller plant with spikelets untidily arranged and upper lemma very shortly awned; U. trichopus, an annual with slightly shorter, thicker and hairier racemes, a denser tufted grass than U. mosambicensis  with longer leaves and 5-nerved lower glume.