Plants not cespitose. Culms acutely angled, 10-90 cm, glabrous. Leaves: basal sheaths red-brown; sheath apex U-shaped; blades hypostomic, glabrous, 3-6 mm wide. Inflorescences: proximal bract shorter than inflorescence, 0.5-3 mm wide. Spikes erect; proximal 2-4 spikes pistillate, 1-2.5 cm × 3-5 mm, base cuneate; terminal 1-2 spikes staminate. Pistillate scales purple-brown, equaling perigynia, apex obtuse or acute, awnless. Perigynia ascending, pale brown with red-brown spots on apical 1/2, veinless, somewhat flattened, loosely enclosing achenes, ellipsoid or obovoid, 2-4 × 1.2-2.3 mm, dull, apex obtuse or acute, papillose; beak red-brown, 0.2-0.3 mm. Achenes not constricted, dull.

Carex scopulorum is the common species of sect. Phacocystis in subalpine, seasonally wet meadows in the western mountains. It is replaced on the western slope of the Cascade range by C. spectabilis, a member of sect. Scitae. Where sympatric with C. aquatilis, C. scopulorum occurs in drier portions of the habitat.

Carex scopulorum is frequently confused with members of sect. Racemosae because of the similarity in habitat, size, inflorescence dimensions, and perigynium shape; it is distinguished by the two stigmas and flattened achenes. Carex scopulorum is probably most closely related to C. bigelowii, based on the similarity in vegetative morphology, hypostomic leaves, perigynia characteristics (absence of veins), and chromosome numbers.