Plants cespitose. Culms straight, 10-50 cm, tallest ones 25-50 cm. Leaves of flowering stems usually shorter than culms, 5-20 cm × 1.5-2.9 mm; ligules on distal cauline leaves truncate or rounded. Inflorescences: peduncles of terminal staminate spikes 0.5-8 mm, 0.2-0.5 length of staminate spikes; bracts to 20 cm × 1.1-2.9 mm, 1.5-4 times as long as inflorescences; inner band of sheaths concave or truncate. Spikes: proximal pistillate spikes (1-)2-5, approximate, subsessile or short-pedunculate, globose to elliptic, 8.5-19.9 × 4.1-9.8 mm; terminal staminate spikes pedunculate, 12-21 × 1.3-2.7 mm. Scales: pistillate scales yellowish green, inconspicuous among perigynia, 1.7-2.6 × 0.8-1.2 mm; staminate scales yellowish green, ovate, 2.9-4.4 × 0.8-1.6 mm, apex obtuse or acute to acuminate. Anthers 1.1-2.9 mm. Perigynia reflexed, yellowish green, 3.5-4.8 × 1.1-1.7 mm, apex gradually narrowed; beak 1.4-2.5 mm, forming an angle of 13-48° with body, smooth. Achenes 1.2-1.5 × 1-1.2 mm. 2n = 64. Fruiting Jun-Aug. Acidic, sandy or organic substrates on open, emergent shorelines, not found on lime-rich soils; 0-500 m; N.B., Nfld. and Labr., N.S., Ont., Que.; Conn., Ind., Maine, Mass., Mich., Minn., N.H., N.J., N.Y., Ohio, R.I., Vt., Wis. The name Carex flava var. fertilis Peck has been misapplied to C. cryptolepis.