Herbs, perennial, rhizomatous, tosometimes nearly cespitose, 0.8--7 dm. Rhizomes usually tuberous, 2--4 mm diam. Culms erect, terete, 1--3 mm diam., smooth. Cataphylls 0--1. Leaves: basal 1--2, cauline 2--3, green; auricles 1--2 mm, apex rounded, membranaceous; blade terete, 2--23 cm x 1--2 mm, distal cauline leaf blade 1.6--26 cm, equaling or longer than sheath. Inflorescences terminal panicles of 1--23(--32) heads, 2.5--9 cm, branches ascending to erect; primary bracts erect; heads 20--60-flowered, spheric or usually lobed, 6--11 mm diam. Flowers: tepals green to straw-colored, lance-subulate, 2--3.5 mm, nearly equal, apex acuminate; stamens 3, anthers 1/3 filament length. Capsules exserted, straw-colored, 1-locular, lance-subulate, 3--4 mm, apex tapering, remaining attached at tip, valves not separating at dehiscence, fertile throughout or only proximal to middle. Seeds oblong, 0.4 mm, not tailed; body clear yellow-brown. Fruiting early summer--fall. Wet sandy soil, salt marshes, lake shores, ditches, meadows, wet woods; 0--1400 m; Ala., Ark., Del., D.C., Fla., Ga., Ill., Ind., Kans., Ky., La., Md., Mich., Miss., Mo., Nebr., N.J., N.Y., N.C., Okla., Pa., S.C., Tenn., Tex., Va. , W.Va.