Plants cespitose or not, short-rhizomatous. Culms solitary or not, erect, (15-)30-80(-140) cm. Leaves 6-12; basal sheaths purplish red; sheath of distal leaf 0-1(-2.5) cm; ligules rounded, 1-8 mm; blades 8-27 cm × 3.5-8 mm. Inflorescences 2-15 cm; peduncles of proximal pistillate spikes 0.3-1.5 cm, basal 2 peduncles 0.2-2.1 cm apart; of terminal spike 0.5-4 cm; bracts leafy, sheathless, blades 6-21 × 2-6 mm. Spikes: proximal pistillate spikes 1-4, often closely aggregated and difficult to distinguish, 1-12-flowered, ovoid to obovoid, 1-2.7 × 1-2.8 cm; terminal staminate spike 1, 1-5 cm × 1-3 mm. Pistillate scales 1-3-veined, lanceolate-ovate to ovate, 4-9.5 × 2-3.8 mm, apex acute to awned, awns rough, to 6.5 mm. Anthers 3, 2-4 mm. Perigynia ascending to spreading or the basalmost reflexed, strongly 13-23-veined, lanceoloid to ovoid, 10-16.5 × 2.5-6.5 mm, with satiny luster, glabrous; beak poorly defined, 2-4.2 mm. Achenes sessile, ellipsoid to obovoid, flat to convex faces, angles not thickened, 3.5-5.7 × (2.2-)2.5-3.9 mm; style same texture as achene. Fruiting late spring-early summer. Dry-mesic to wet coniferous, mixed, and deciduous forests, forest openings, thickets, wet meadows, ditches; 0-2000 m; Man., N.B., Nfld. and Labr., N.S., Ont., P.E.I., Que.; Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., N.H., N.J., N.Y., N.C., Ohio, Okla., Pa., R.I., S.C., S.Dak., Tenn., Tex., Vt., Va., W.Va., Wis. Plants from the south of the species range and from lower elevations northward are usually more robust and have more inflated, ovoid perigynia than northern or high-elevation plants. The latter are sometimes distinguished as Carex intumescens var. fernaldii L. H. Bailey.
Much like no. 225 [Carex grayi J. Carey]; pistillate spikes 1-4, 1-2.7 cm long and wide, ovoid to obovoid, loosely fld, on peduncles to 1.5 cm, often closely aggregated; perigynia 1-12, mostly spreading or ascending, with a satiny lustre, 10-16.5 נ2.5-6.5 mm, convexly rounded to the base, the poorly defined beak 2-4.2 mm; achene 3.5-5.7 נ2.5-4 mm, with flat or convex faces; 2n=48. Moist or wet woods; Nf. to se. Man., s. to Fla. and Tex.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Frequent to locally common in depressions in low woods (maple, beech, sweet gum or pin oak) and in flat woods. [Variety fernaldii, with narrower, shorter perigynia, is] infrequent in northern Indiana, chiefly in the lake area, in habitats similar to those of the species.