Description from Flora of China
Tema Adanson, nom. rej.
Annual or perennial. Culms often coarse and robust. Leaf blades flat, linear or broadly linear; ligule absent (ciliate in some species outside China). Inflorescence composed of racemes along a central axis; racemes simple or compound, densely spiculate, spikelets paired in 4 rows, or congested on secondary racemelets. Spikelets narrowly elliptic to subrotund, plump, plano-convex, often hispidulous or spinulose, acute to awned; lower glume triangular, 1/3–1/2(–3/5) spikelet length, sheathing; upper glume and lower lemma equaling the spikelet or upper glume somewhat shorter in cultivated forms, prominently 5–7-veined, acute to rostrate or lower lemma extended into a stout awn; upper lemma coriaceous, smooth, shining, terminating in a short, laterally compressed, incurving beak; upper palea acute, apex briefly reflexed. x = 9.
The reflexed upper palea tip, although a very tiny character, is nevertheless important for distinguishing Echinochloa from neighboring genera, especially Brachiaria. The absence of a ligule is also a good spot character for recognition of the genus in China.
Species of Echinochloa typically grow in aquatic or moist situations. Several have become widespread weeds, especially of irrigated crops, and two are sometimes cultivated as minor cereals.
About 35 species: tropical and warm-temperate regions of the world; eight species (at least one introduced) in China.
(Authors: Chen Shouliang (陈守良); Sylvia M. Phillips)