Description from Flora of China
Perennials, often robust, sometimes rhizomatous. Leaf blades linear, usually flat; ligule membranous. Inflorescence a panicle, loosely contracted to dense and spikelike, often plumose, branches usually whorled, bearing numerous spikelets. Spikelets with 1 floret; rachilla disarticulating above glumes, extension beyond floret absent or small and glabrous, rarely better developed and penicillate; glumes persistent, subequal or unequal with lower longer, narrowly lanceolate, much exceeding floret, lower glume 1-veined, upper glume 3-veined at base, apex finely acuminate or subulate; floret callus conspicuously bearded, hairs much exceeding floret; lemma ca. 1/2 as long as glumes, hyaline, 3–5-veined, awned, apex erose, denticulate or deeply 2-lobed; awn very slender, straight or almost so, arising from lemma back, apex or between teeth; palea 1/2 as long to slightly shorter than lemma. Stamens usually 3, rarely 1.
Calamagrostis intergrades with both Agrostis and Deyeuxia, and the number of species in the genus is very uncertain. As in Deyeuxia, the taxonomy is complicated by polymorphic species complexes arising from polyploidy, apomixis, and hybridization.
About 20 species: N temperate and arctic regions; six species (one endemic) in China.
(Authors: Lu Shenglian (卢生莲); Sylvia M. Phillips)