Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Genus Description - Spikelets 2–5-fld, disarticulating above or below the glumes; glumes large, membranous, 3–5-veined; lemmas rounded on the back, 5–7-veined, or with additional veins near the base, obtuse or acute, awned or awnless; uppermost 1–4 lemmas much smaller, sterile and often distinctly unlike the fertile ones; slender, tufted to rhizomatous grasses with closed sheaths, flat lvs, conspicuous ligules, and sparsely branched, few-fld panicles. 50+, mostly temp. regions.