Culms 5-15 dm, often branched above, smooth, clustered on creeping rhizomes; sheaths glabrous or nearly so; ligules 3-8 mm; blades scabrous on both sides, flat, 4-8 mm wide; infl somewhat nodding, 8-25 cm, open or fairly dense, but not contracted, the longer branches 3-8 cm; spikelets 2-6 mm; glumes subequal or the second slightly longer, acute to acuminate, rounded or keeled, glabrous to scabrous-puberulent on the sides; lemma nearly or quite smooth, translucent at the dentate or erose tip, three-fourths to fully as long as the glumes; awn delicate, erect, straight or nearly so, inserted near the middle of the lemma; callus-hairs abundant, nearly as long as the lemma; rachilla-vestige 0.1-0.3 mm, hairy throughout; 2n=42-66. Open swamps, wet meadows, and prairies, or moist or wet soil in the mts.; Greenl. to Alas., s. to N.C., Mo., and Ariz. Highly variable, but not readily divisible into vars. (C. macouniana, the small-fld extreme; C. langsdorffii, the large-fld extreme; C. nubila)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
