Plants not cespitose. Culms acutely angled, 30-110 cm, scabrous. Leaves: basal sheaths red-brown; sheaths of proximal leaves bladeless, scabrous, fronts with red-brown spots, prominently ladder-fibrillose, apex red-brown, U-shaped; blades hypostomic, 4-7 mm wide, papillose abaxially. Inflorescences: proximal bract subequal to inflorescence, 3-6 mm wide. Spikes erect; staminate 1-2; pistillate 3-4; proximal pistillate spike 2.5-7 cm × 3-5 mm, base attenuate. Pistillate scales red-brown or black, longer than perigynia, apex acute, awnless. Perigynia ascending, pale brown with red-brown spots on apical 1/2, 1-3-veined abaxially, somewhat flattened, loosely enclosing achenes, ellipsoid or obovoid, 2.2-3 × 1.2-2 mm, dull, apex obtuse or acute, papillose; beak red-brown, 0.2-0.5 mm. Achenes not constricted, dull. 2n = 66, 68.

Fruiting Jul-Aug. Wet meadows along streams; 300-2300 m; Calif., Idaho, Oreg., Wash.

Carex angustata is a member of the C. stricta complex based on the scabrous, red-brown, bladeless ladder-fibrillose sheaths, the veined perigynia, the hypostomic leaves, and the low chromosome numbers. It is distinguished from sympatric members of the group, C. nudata and C. senta, by the rhizomatous habit, the few-veined perigynia, and the scabrous stems and from the often-sympatric C. aquatilis by the scabrous, veined sheaths and the veined perigynia.