Description from Flora of China
Annual or perennial. Leaf blades linear, not aromatic; ligule scarious or reduced to a line of hairs. Inflorescence simple or compound; racemes fragile, usually paired, occasionally digitate or single, terminal on the culm or axillary and gathered into a spathate compound panicle; spikelets of a pair dissimilar; raceme bases not deflexed, without homogamous spikelets (present in A. munroi); rachis internodes filiform to linear or clavate, sometimes inflated, ciliate on margins. Sessile spikelet usually dorsally compressed; callus short, obtuse, shortly bearded, inserted into internode apex; lower glume membranous to leathery, 2-keeled, lanceolate, flat to concave with lateral keels, these sometimes narrowly winged, with or without intercarinal veins, or linear with dorsal keels and a deep veinless median groove; upper glume awned or awnless; lower floret reduced to a hyaline lemma; upper lemma hyaline, 2-lobed, awned from sinus; awn geniculate, column glabrous or puberulous. Stamens 1–3. Pedicelled spikelet variable, large to much reduced, male or barren. x = 10.
About 100 species: tropical and warm-temperate regions of both hemispheres, especially Africa and America; two species in China.
(Authors: Chen Shouliang (陈守良); Sylvia M. Phillips)