Plants loosely cespitose or colonial. Culms erect, straight, bluntly trigonous, 8-40 cm, smooth to slightly scabrous-angled distally. Leaves: basal sheaths dark brown; ligules 0.4-1.7 mm; blades flat, shorter than culms, (1.5-)2-3.5(-4) mm wide. Inflorescences 0.8-1.6 cm; spikes ca. 5-15, indistinguishable in dense, globose to ovoid head. Pistillate scales reddish brown to blackish, ± translucent, lacking whitish hyaline margins, ovate, ± equaling perigynia, apex acute to acuminate, body shiny. Anthers 1.5-2.8 mm. Perigynia pale yellowish brown proximally, reddish brown to blackish distally and on beak, finely 5-9-veined abaxially, faintly veined or essentially veinless adaxially, flattened, not inflated, narrowly to broadly elliptic, 3.3-4.6 × 1.1-1.9 mm, membranous, shiny; stipe 0.2-0.6 mm; beak well defined, 0.9-1.5 mm, smooth-margined.

Fruiting Jul-Sep. Moist alpine tundra, moist forest openings just below treeline; 2000-3800 m; Calif., Colo., Idaho, Oreg., Wash., Wyo.

Carex vernacula is very similar to and often united with the European C. foetida Allioni, which has serrulate-margined perigynium beak and proportionately longer leaves. The numerous distinctions drawn between these two by K. K. Mackenzie (1931-1935, parts 2-3, pp. 29-30) have not proved consistent with examination of more material.