Herbs, perennial, not cespitose, rhizomatous, (3--)4.5--8(--9) dm. Rhizomes tuberous, 3--4 mm diam. Culms erect, terete, 2--3 mm diam., smooth. Cataphylls 0(--1), straw-colored, apex acute. Leaves: basal 1--2, cauline 2--4, auricles 0.5--3.5 mm, apex rounded, scarious; blade green to straw-colored, terete, 3--50 cm x 1--2 mm diam. Inflorescences terminal panicles of 2--10(--20) heads or a single head, 1--4(--10) cm, branches ascending; primary bract erect; heads 30--100-flowered, spheric, 8--10 mm diam. Flowers: tepals green to straw-colored, often red-tinted, lanceolate-subulate, apex acuminate; outer tepals 2.5--3.8 mm; inner tepals 2--3.2 mm; stamens 3, anthers 1/4--1/2 filament length. Capsules included, chestnut brown, 1-locular, obconic or ovoid, 1.8--2.7 mm, apex obtuse, valves separating at dehiscence, fertile throughout or only proximal to middle. Seeds ellipsoid to oblique-oblong, 0.3--0.4 mm, not tailed; cody clear to yellow-brown. 2n = 44. Fruiting mid summer--fall. Damp clayey, peaty, or sandy soils, swamps, ditches, ponds, wet woods, wet prairies; 0--500 m; Ont.; Ala., Ark., Conn., Del., Fla., Ga., Ill., Ind., Kans., Ky., La., Md., Mass., Mich., Minn., Miss., Mo., N.J., N.Y., N.C., Ohio, Okla., Pa., S.C., Tenn., Tex., Va., W.Va.