Description from Flora of China
Annual or perennial, tufted or rhizomatous. Leaf blades linear, flat; ligule membranous. Inflorescence a contracted or spikelike panicle. Spikelets strongly laterally compressed, florets 3 with lower 2 usually reduced to sterile lemmas and uppermost floret bisexual, disarticulating above glumes, rachilla not or very rarely extended beyond uppermost floret; glumes subequal, boat-shaped, as long as spikelet and enclosing florets, herbaceous, prominently 3-veined, strongly keeled and often winged along midvein; sterile lemmas up to 1/2 as long as fertile lemma, narrow, often hairy, or one or both reduced to a vestigial fleshy scale at base of fertile floret; fertile floret shorter than glumes, leathery often becoming cartilaginous and shiny, rounded on back, obscurely 5-veined, awnless; palea resembling lemma, 2-veined. Caryopsis tightly enclosed by lemma and palea; embryo small; hilum linear. x = 7.
Eighteen species: mainly in the Mediterranean region and warm-temperate parts of the New World, one species circumboreal; several species widely distributed as adventives; five species (four introduced) in China.
(Authors: Wu Zhenlan (吴珍兰); Sylvia M. Phillips)