Description from Flora of China
Annuals or perennials, tufted or sometimes with rhizomes or stolons. Leaf blades linear to filiform or setaceous, flat or rolled; ligule membranous. Inflorescence a panicle, open to contracted or spikelike. Spikelets with 1 floret, small, often gaping, without rachilla extension; rachilla disarticulating above glumes; glumes persistent, longer than floret, subequal or lower a little longer, membranous, 1-veined, apex subacute to acuminate; floret callus glabrous or shortly pilose; lemma oblong to elliptic, thinner than glumes, often hyaline, 5-veined, rounded on back, glabrous or hairy, lateral veins sometimes excurrent, awnless or awned from back, apex truncate or toothed; awn usually geniculate, sometimes weakly so or straight when short; palea shorter than lemma, sometimes very small. Stamens 3. Caryopsis oblong, sulcate on ventral side.
The genus includes some good fodder and lawn plants.
Some species are superficially very similar, and correct identification depends on careful observation of spikelet details. It is also important to collect the basal parts to show the presence or absence of rhizomes and stolons. When the palea is long it is normally obvious, but small paleas usually adhere to the mature caryopsis and may appear to be absent. The presence or absence of awns is useful for identification, but awned species may have awnless variants, and vice versa, and the position of the awn on the lemma back can also be rather variable.
About 200 species:temperate and cold regions of the N hemisphere, also on tropical mountains; 25 species (eight endemic) in China.
(Authors: Lu Shenglian (卢生莲); Sylvia M. Phillips)