Culms trigonous in cross section, (25–)30–110 cm; vegetative culms hard, solid with parenchyma, taller than fertile culms. Leaves: basal sheaths reddish purple, inner bands fibrillose with age; sheaths with apex of inner band pale to dark brown, translucent between veins, strongly veined, becoming ladder-fibrillose, glabrous, veins scabrous; ligules 2–12(–17) mm; blades 3–6 mm wide, glabrous, not papillose abaxially. Inflorescences (9–)15–65 cm; spikes erect or ascending; proximal 2–4 spikes pistillate; terminal 2–5 spikes staminate. Pistillate scales lanceolate to narrowly ovate, apex acute to acuminate, scabrous-awned, otherwise glabrous. Staminate scales lanceolate to narrowly ovate, apex obtuse to acuminate, occasionally with scabrous awn, glabrous. Perigynia 12–26-veined, (4.4–)4.8–8.4 × 1.8–3.3 mm, glabrous or scabrous on veins; beak straight to slightly spreading, 1.7–3.8 mm, glabrous or sparsely scabrous-pubescent, teeth (0.8–)1.1–2.3 mm.

Fruiting May–Jul. Openings in bottomland and lowland forests, edges of marshes, lakes, and ponds, wet meadows, wet thickets, mesic to wet prairies and savannas; 140–600 m; Man., Ont., Sask.; Ill., Iowa, Kans., Minn., Mo., Mont., Nebr., N.Dak., S.Dak., Wis.

Carex laeviconica is characteristic of wetlands in the northern Great Plains and western portions of the tallgrass prairie region.

Carex laeviconica hybridizes with C. trichocarpa.