Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Spikelets turgid, with one perfect terminal fl and a neuter or sometimes staminate floret below, sessile or subsessile, articulated and eventually deciduous above the persistent subtending bristles (or even above the glumes and sterile lemma), crowded into a dense and spike-like panicle with many nodes and short branches, each branch-system with numerous reduced sterile branches forming the prominent bristles; first glume triangular to ovate, 3- or 5-veined, up to nearly half as long as the spikelet; second glume several-veined, longer, up to as long as the spikelet; sterile lemma glume-like, about equaling the fertile one, usually with a well developed palea; fertile lemma indurate, smooth or more often transversely rugulose, its margins revolute and clasping a palea of similar texture. 140, cosmop., mostly in warm regions.