Description: Tufted annual or rarely rhizomatous perennial herbs. Culms erect, glabrous, nodeless.
Leaves basal, elongate; ligule absent.
Inflorescence of 1–8 sessile, head-like spikes, subtended by a few leaf-like involucral bracts. Spikes cylindrical or ovoid, with thick central axis bearing many spikelets. Spikelets 1-flowered, with spikelet bract subtending 2 hyaline scales (= spikelet prophyll and glume) that enclose flower. Flowers bisexual. Scales hyaline, sometimes reduced or absent. Stamens 1–3. Style 2- or 3-fid, not enlarged at base, not persistent.
Nut dorsiventrally compressed, trigonous or plano-convex, often slightly curved.
Distribution and occurrence: World: 35 species, tropical. Australia: 2 species (native), all mainland States.
This genus has a very reduced inflorescence. In the past, the spikes have been interpreted as many-flowered spikelets, the spikelet bract as a glume, and the two hyaline scales (= spikelet prophyll and glume) as perianth scales.
Text by K. L. Wilson