Culms ascending to arching, filiform, 30-90 cm. Leaves mid to deep green, (0.5-)1-1.5 mm wide. Inflorescences flexible, 1.5-4(-7) cm; proximal spikes 0.5-2.5 cm apart; terminal spike often clavate. Perigynia (1.5-)2-2.5 × 0.8-1.25 mm. 2n = 56.

Fruiting May-Jul. Damp, temporarily dry areas, thin-peated mires, thickets, woodlands, heaths, rocky slopes; 0-3500 m; St. Pierre and Miquelon; Man., N.B., Nfld. and Labr., N.S., Ont., P.E.I., Que.; Conn., Del., Ga., Ind., Maine, Md., Mass., Mich., Minn., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., Tenn., Vt., Va., W.Va., Wis.; Eurasia.

The complete distribution of Carex brunnescens subsp. sphaerostachya is still unclear. See note under subsp. brunnescens.