Plants loosely cespitose. Culms 30-100 cm. Leaves: sheaths papillose, summits U-shaped; distal ligules 2.1-4.6 mm; blades 3-4 per fertile culm, 18-23 cm × 2-4 mm. Inflorescences stiffly erect, open, coppery brown, 1.5-3.4 cm × 6-15 mm; proximal internode (1-)3-6(-9) mm; 2d internode 1-4 mm; proximal bracts usually scalelike, occasionally bristlelike. Spikes (3-)5-6(-10), distant, individually distinct, rhomboid-ovoid, 5-10 × 3-7 mm, base and apex tapered. Pistillate scales mid to dark brown, usually with pale midstripe, glossy, lanceolate, (3-)3.5-3.7(-4) mm, subequal to perigynia in length and width, margin white-hyaline, to 0.15 mm wide, apex acute. Perigynia ascending, light green to straw colored, pearlescent, often with adaxial reddish brown blotch, conspicuously 7-15-veined abaxially, usually inconspicuously or conspicuously (6-) 9-12-veined adaxially, lanceolate, plano-convex, 2.9-4.3 × 0.9-1.4 mm, 0.6 mm thick, margin flat, including wing 0.07-0.4 mm wide, unwinged below median; beak brown, white-hyaline at tip, flat, ciliate-serrulate, abaxial suture conspicuous, often with narrow white-hyaline margin, distance from beak tip to achene 1.5-2.4 mm. Achenes ovate, 1.3-1.6 × 0.7-1.4 mm, 0.3-0.5 mm thick. 2n = 74. Fruiting summer (late Jun-mid Jul). Hay fields, forest edges, open woods; of conservation concern; 30-400 m; Maine. Carex oronensis is in the Center for Plant Conservation´s National Collection of Endangered Plants.