Culms to 120 cm × 3 mm. Leaf blades green, to 60 cm × 10 mm. Inflorescences to 10 × 3 cm. Perigynia 4-5 × 2 mm; beak to 2.5 mm. 2n = 48 (Japan), 52.

Fruiting Jun-Aug. Seasonally saturated or inundated soils in wet meadows, marshes, edges of tidal marshes, swamps, alluvial bottomlands; 0-1700 m; St. Pierre and Miquelon; Alta., B.C., Man., N.B., Nfld. and Labr., N.S., Ont., P.E.I., Que., Sask.; Alaska, Ariz., Calif., Colo., Conn., Del., D.C., Idaho, Ill., Ind., Iowa, Kans., Ky., Maine, Md., Mass., Mich., Minn., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo.; e Asia.

Very common in wet habitats throughout Indiana. It is usually found on borders of ponds and streams and in low woods, roadside ditches, swamps, marshes, bogs, and woodland swales.