Rhizomes to 10 cm × 2 mm. Culms 0.3-1 m × 1-2 mm. Leaves: blades conduplicate to sub-involute, (1-)2-3.5 mm wide, smooth or nearly so. Inflorescences terminal or lateral and terminal, pedunculate, peduncle mostly covered by subtending leaf sheath, 15-25 cm; 1st and 2d order branches (rarely congested and with little obvious branching), branches stiffly ascending. Spikelets in groups of 3-5(-30), narrowly ellipsoid to lanceoloid; floral scales 5-6, the proximal chestnut brown, ovate to oblong-lanceolate, 2.5-3 × 2 mm, midvein conspicuous, lateral veins weak; stamens 2; anthers 2 mm, connective apices 0.1 mm; styles 2-2.5 mm; stigmas 1-1.5 mm. Achenes whitish or pale green, ovoid, 2.5-3 × 1.5-1.7 mm, base 3-6-lobed, discoid, truncate and impressed, flared, apex subacute, irregularly rugulose longitudinally, glossy. Fruiting summer-early fall. Open acidic to alkaline wetlands, brackish upper edges of tidal marshes; 0-400(-1200) m; Man., N.B., Nfld. and Labr., N.S., Ont., Que., Sask.; Conn., Del., Fla., Ill., Ind., Maine, Md., Mass., Mich., Minn., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Tenn., Tex., Vt., Wis.
Culms stiff, slender, to 1 m, solitary or few together from rhizomes, often colonial; blades 1-3 mm wide, channeled toward the base, flat or nearly so in the middle, becoming terete distally, smooth or nearly so; infl slender, the terminal cyme 5-10 cm, the lower ones remote; spikelets lanceolate, becoming ovoid, 3-5 mm; lower scales short, subrotund, the upper ovate; achene dull brown, 2.5-3.5 mm, conspicuously pointed, the base either contracted or broadly truncate. Swamps and marshes, usually in calcareous or saline places; N.S. to Minn., s. to w. Fla. and Ky.; e. Tex. (Mariscus m.) Some plants have the infl much congested.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.