Plants densely cespitose; rhizome internodes 0.2-7 mm, 1.2-2.2 mm thick. Culms sparingly purple-red to 2.7-5.2(-5.6) cm high at base, 14-37 cm; longest vegetative shoots 23-45 cm, (0.8-)1.4-1.6 times as tall as culms. Leaves: nonbasal sheaths glabrous; blades green, widest blades 2.6-4 mm wide, smooth abaxially. Inflorescences 19-34 cm, (0.88-)0.94-0.99 of culm height; internode between proximalmost scales in proximalmost spike 3-4.3 mm; internode between distal lateral spikes (1-)2.6-12 cm; longest internode (per plant) between distal lateral spikes 5.2-12 cm; peduncle of terminal spike 3.1-54(-73) mm, longest per plant 17-54(-73) mm; proximal bract sheaths tight, apex concave or truncate; ligules 1-4.9(-9.6) mm; blades uniformly green, blade of distalmost lateral bract exceeding terminal spike, longest (per plant) bract blade of distalmost lateral spike 6.1-15 cm. Spikes 4-5 spikes, widely separate or distal 2-3 spikes overlapping, proximalmost spike usually basal; lateral spikes pistillate, with 2-8 perigynia, longest spikes per plant with 5-8, 11-17 × 4.5-8.5 mm, ratio of longest lateral spike length (in mm) to flower number = 2.2-2.4; terminal spike 8-35 × 1.4-2.5 mm, longest per plant 14-35 mm, exceeding distlmost lateral spike. Pistillate scales 3.6-5.7 × 1.8-2.1(-2.4) mm, body (2.2-)2.5-3 mm, midrib prolonged as awn 01-3.2 mm. Staminate scales 4.3-5.8 × 1.4-1.9 mm, apex usually acute, occasionally obtuse, awnless. Anthers 3.8-4.2 mm. Perigynia distichously imbricate, prominently 48-63-veined, obovate or narrowly obovate, obtusely trigonous in cross section, (3.7-) 3.9-5 × 1.6-2(-2.1) mm, 2.1-2.5(-2.7) times as long as wide, 1.5-2 times as long as achene bodies, base gradually tapered, apex contracted; beak straight or excurved 10-30°, (0.4-)0.6-1 mm, 0.08-0.21 of perigynium length. Achenes, 2.6-3.4 × 1.4-1.9 mm, body 2-2.6 mm, tightly enveloped by perigynia; stipe straight, 0.2-0.5(-0.7) mm; beak straight, (0.1)-0.2(-0.3) mm.

Fruiting spring. Mesic deciduous forests, in sandy loams and sands, usually on stream banks slopes; of conservation concern; 0-40 m; Fla., Ga., N.C., S.C.

Carex calcifugens is rare, local, and usually occurs in small populations. It frequently associates with C. abscondita and C. striatula.