Tufted, 3-6 dm; fertile stems triangular, roughened on the angles, purple at base; basal sheaths purple; lvs smooth, those of the sterile shoots 10-25 mm wide, of the fertile ones only 2-6 mm wide; terminal spike staminate, 1-2 cm, purplish, pedunculate; pistillate spikes 2 or 3, 0.7-2 cm, scattered, the lowest sometimes basal; pistillate scales acute to cuspidate; perigynia 4-7, overlapping, 5-6.5 mm, finely many-nerved as well as 2-ribbed, sharply trigonous, elliptic-ovate in outline, tapering to a slightly oblique beak with entire orifice; achene sharply trigonous; 2n=68. Rich woods, often calciphile; N.Y. to s. Ont., Mich. and Io., s. to Va., Ala., and Mo.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.