Culms 10-105 cm. Leaves 3-8 per culm; sheaths tight, inner band hyaline, 4-23 cm, apex concave, ± glabrous; ligules rounded to obtuse, 0.9-2.5 mm; blades plicate, 11-45 cm × 1.7-5 mm, widest leaf 2.8-5 mm wide. Inflorescences (0.8-)1.5-3 cm; spikes 4-6; lateral spikes gynecandrous, 4.5-8 mm, sessile, staminate portion (0-)1-3-flowered, (0-)0.5-2 mm, pistillate portion 5-21-flowered, 3-8 mm; basal 2 spikes 1.3-9.5 mm apart; terminal spike androgynous, 6.1-14.5 mm, staminate portion 5-20-flowered, 2-8.6 × 0.8-1.3 mm, pistillate portion 7-25-flowered, 3-8 × 5-7.3 mm. Pistillate scales ovate, 1.45-2(-2.2) × 1.3-1.9 mm, apex obtuse to acute, sometimes shortly mucronate. Staminate scales ovate, 1.2-2.3 × 1.4-1.8 mm, apex obtuse to acute. Anthers 0.7-1.3 mm. Perigynia spreading to reflexed, green to castaneous, 5-18-veined abaxially, faintly 0-10-veined adaxially, broadly ovate, 2.55-3.75 × (1.25-)1.4-2(-2.1) mm, (1.4-)1.6-2.5 times as long as wide; beak 0.55-1.1(-1.35) mm, 0.25-0.55 length of body, serrulate, teeth 0.2-0.5 mm. Achenes ovate, 1.4-1.9 × 1.1-1.55 mm.

Fruiting late spring-early summer. Bogs, openings in acidic conifer, mixed, or alder swamps, wet acidic sandy or peaty meadows; 0-1300 m; St. Pierre and Miquelon; N.S., Nfld. and Labr., N.S., Ont., P.E.I., Que.; Maine, Mass., Mich., N.H., N.Y., Pa., Vt.

A putative hybrid between Carex wiegandii and C. echinata subsp. echinata has been collected in Michigan.