Plants with short-creeping rhizomes, loosely cespitose, forming colonies. Culms brown at base, densely covered with brown fibrillose remains of previous year´s leaves; flowering stems 30-90 cm, longer than leaves at maturity, 0.5-0.7 mm thick, glabrous but finely scabrous within inflorescence. Leaves: sheaths glabrous, basal ones tinged with brown and all bearing blades, green to hyaline on back, white-hyaline on front; blades flat, 2.5-4 mm wide, finely scabrous on adaxial surface and margins, glabrous on abaxial surface. Inflorescences: peduncles of lateral spikes slender, 20-60 mm, equaling or somewhat longer than spikes, finely scabrous; peduncle of terminal spike 5-15 mm, scabrous; proximal bracts equaling inflorescences or more often shorter; sheaths 3-5 mm or rarely longer; blades 1-1.5 mm wide. Lateral spikes 4-5, 1 per node; proximal spikes well separated, nodding or drooping at maturity, pistillate with 10-40 perigynia about 1 mm apart, cylindric, 10-35 × 8-10 mm; distal spikes crowded near apex, sessile or nearly so, staminate or androgynous, linear, less than 20 mm. Terminal spike staminate or rarely with a few perigynia at base, 10-20 × 1.5-2 mm. Pistillate scales pale hyaline tinged with chestnut, narrow midrib green, sometimes finely scabrous, ovate-oblong, shorter than mature perigynia, apex long-acuminate, glabrous. Perigynia shiny tan to golden green, 2-ribbed, but otherwise veinless, closely enveloping achene at maturity, ovoid-ellipsoid, 4.5-6.5 × 1.5-2 mm, membranous, base acute, apex abruptly contracted to beak, glabrous; beak bidentate, narrowly tubular, nearly as long as body, finely scabrous on edge, teeth hyaline, 1 mm. Achenes substipitate, 2-2.5 × 1.7-1.8 mm. 2n = 42. Fruiting early to mid summer. Dry to mesic deciduous forests and forest openings, floodplain forests and riverbanks, lakeshores, limestone river bluffs, mixed conifer-hardwood forests, thickets, meadows, roadsides, often associated with calcareous rocks and soils; Alta., B.C., Man., N.B., Ont., Que., Sask.; Colo., Conn., Del., Ill., Ind., Iowa, Maine, Mass., Mich., Minn., Mo., Mont., Nebr., N.H., N.J., N.Y., N.Dak., Pa., S.Dak., Vt., Wis., Wyo.
Stems 4-8 dm, clustered on a stout, short or somewhat elongate rhizome that is densely covered with old fibrous lf-remains; lvs cauline as well as basal, elongate, mostly 1.5-4 mm wide; terminal 1 or 2 spikes staminate or with a few basal perigynia, 1-2 cm, the others 2-4, pistillate or the upper with a few distal staminate fls, 1.5-3.5 cm, 10-30-fld, not crowded, at least the lower ones loose to spreading or nodding on long, capillary peduncles; lowest bract with sheathing base 1-10 mm and long, slender blade, the others more reduced and often sheathless; pistillate scales narrow, acute or acuminate, pale, largely scarious or hyaline, often scabrous along the midrib, surpassing the body of the perigynium; perigynia 4.1-7.7 mm, the body broadly ellipsoid or ellipsoid-obovoid, prominently 2-nerved, 2.2-3.8 mm, abruptly contracted to the slender softly bidentate beak 1.7-4 mm; achene trigonous, the persistent style-base commonly contorted; 2n=42. Open woods, meadows, and rocky ledges; N.B. to B.C., s. to N.J., Io., and Colo. (C. longirostris, a preoccupied name)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.