Plants annual or perennial; cespitose or tufted, often stoloniferous. Culms 12-80 cm, herbaceous, unbranched distally. Leaves involute to flat; ligules membranous, ciliate. Inflorescences terminal, panicles of several, racemosely arranged, spikelike branches, mostly exceeding the leaves, lower branches sometimes partially included in the upper leaf sheaths at maturity; branches not woody, unilateral, with 2 rows of appressed, imbricate, solitary spikelets, terminating in a rudimentary, sterile spikelet, sterile spikelets sometimes consisting of 1 or 2 small scales. Spikelets dorsally compressed, with 1 floret; disarticulation below the glumes. Lower glumes to 2/3 as long as the spikelets, veinless; upper glumes equaling the florets, 1-veined; calluses acute to pointed; lemmas thinly membranous, 3-veined, apices rounded to acute, mucronate, shortly awned, or unawned. Caryopses ellipsoid. x = 10. Named for Heinrich Moriz Willkomm (1821-1895), a German botanist and explorer.