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.
Stems stout, 5-12 dm, arising singly or few together from long rhizomes, aphyllopodic, the lower sheaths soon breaking and becoming strongly fibrillose; lvs glabrous, the main ones 3-6 mm wide, usually evidently cross-septate; staminate spikes ca 3, distal; pistillate spikes 2-4, very remote, cylindric, 3-7 cm, densely fld, erect, sessile or short-peduncled, sometimes staminate at the top; bracts lf-like but scarcely or not at all sheathing, equaling or surpassing the infl; pistillate scales thin, hyaline or pale brown, the body usually much shorter than the perigynium, either acuminate or obtuse with the green midvein prolonged into an awn nearly or quite equaling the perigynium; perigynia 5.5-9 mm, broadly ovoid, conspicuously many-nerved, tapering into a slender, minutely scabrous beak with nearly straight, moderately divergent, scabrous teeth 1-2.2 mm; achene trigonous, loosely enveloped, with a persistent, straight, slender style; 2n=110. Swales and borders of ponds; Ill. and Mo. to Sask.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.