Culms 35-100 cm, angles scabrous. Leaves: basal sheaths leafless, usually red-brown; blades amphistomic, 5-8 mm wide, papillose on both surfaces. Inflorescences: peduncle of proximal spike not more than 4 cm; proximal bract longer than inflorescence, 4-8 mm wide. Spikes erect; proximal 3-4 spikes pistillate, 2-4 cm × 4-7 mm, base cuneate or attenuate; terminal 1-3 spikes staminate. Pistillate scales pale red-brown with narrow pale midvein. Perigynia obovoid, 2-3 × 1.2-2 mm, apex rounded; beak pale brown, not more than 0.2 mm, thickened. 2n = 76.

Fruiting Jul-Aug. Wet tundra; 0-600 m; Greenland; N.W.T., Nunavut, Que., Yukon; Alaska.

Although extensively intergrading along the Arctic coast, Carex aquatilis var. minor and var. aquatilis appear to be distinct; C. aquatilis var. minor has been reported to maintain its distinctive characteristics in cultivation (J. Cayouette and P. Morisset 1986b). It is reported to hybridize with C. bigelowii (= C. ×nearctica M. Raymond).