Culms 5-40 cm. Leaves: blades 5-15(-25) cm × 1-2.5(-3.5) mm. Inflorescences: proximal bracts leaflike, exceeding inflorescences, sheaths to 10 mm; lateral spikes with 9-30 perigynia, approximate or proximal distant, dense, 7-15 × 3-5 mm; middle internodes 0.3-0.7 mm; terminal spike usually gynecandrous, with at least 1/3 of flowers staminate, rarely entirely staminate, sessile or short-pedunculate, 6-15(-20) mm, (1.2-)1.5-2.5 mm wide in staminate portion. Pistillate scales ascending, medium to dark brown with paler midvein and hyaline margins, ovate-circular, 1.7-2.7 × 1-1.9 mm, apex obtuse to acute, sometimes shortly mucronate. Staminate scales brown with paler midvein and hyaline margins, oblong-ovate, (2-)2.5-3.7 mm, apex obtuse to acute. Perigynia ascending, white, elliptic-obovate, 2-3 × 1.2-1.8 mm, densely papillose. Achenes elliptic-circular, 1.4-2 × 1-1.5 mm.

Fruiting summer. Moist shores, meadows, fens, on base-rich soils; 0-1500 m; Alta., B.C., Man., N.B., N.W.T., Nunavut, Ont., Que., Sask., Yukon; Alaska, Calif., Ind., Maine, Mich., Minn., N.H., N.Y., N.Dak., Ohio, Oreg., Pa., Utah, Vt., Wash., Wis., Wyo.

Infrequent in the lake area (mostly in the dune region) where it grows along the wet sandy edges of swales in the dunes and on old lake beds, chiefly in calcareous soils. It is frequently associated with Carex crawei, C. tetanica, C. meadii, C. viridula, and C. haleana. Apparently it was formerly more plentiful than at present as collections from the Indiana dunes forty and fifty years ago are much more numerous in herbaria than recent collections. At Pine, where this species is closely associated with Carex tetanica, plants of the latter species showing many characteristics of C. Garberi and plants of C. Garberi having characteristics of C. tetanica are frequent. The general aspect of such plants and the conditions under which they are found are strongly suggestive of hybridization.