Culms usually clustered, stout and erect, to 15 dm; lvs 8-12 mm wide; ligule 2-4+ mm; infl 2-4 dm, much branched, usually nodding at the tip; spikelets 4-6.5 mm, 5-9-fld, slightly flattened; rachilla-joints 0.6-1 mm; glumes membranous or scarious, pale or white, acute, the first 1.2-1.9 mm, the second 1.5-2.4 mm; lemmas usually purple, narrowly ovate, with prominently raised veins, gradually tapering from below the middle to the obtuse firm tip; anthers (2)3, 0.5-1 mm; 2n=20. Swamps, marshes, brooksides, and shallow water; Que. and N.S. to Va., w. to the Pacific.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.