Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Spikelets 1-fld, articulated above the glumes; glumes subequal, acute or acuminate, the first usually a little the larger, lemma equaling or shorter than the glumes, inconspicuously 5-veined, tapering to an obtuse or truncate, erose tip, usually thin and membranous, subtended at base by white hairs arising from the callus, and bearing a slender dorsal awn; palea membranous, half to fully as long as the lemma; rachilla prolonged (in our native spp.) behind the palea as a slender, usually hairy, often inconspicuous bristle, perennials, often rhizomatous, with long narrow lvs and a loose and open to contracted and spike-like panicle. 150+, temp. and cool reg. Many of the plants at higher ploidy-levels are apomictic.