Perennials, 20–70 cm tall, caespitose; rhizome short, ±vertical, densely branching. Cataphylls 1–2, stramineous to pink; basal leaves 1–3, 0.2–12 cm long. Cauline leaves 1–2, 0.2–12 cm long, terete to compressed, unitubular, septate; tip blunt; auricles 0.6–1.5 mm long, rounded, scarious. Lower bract leaf-like, terete, 1–5 cm long, shorter than the inflorescence, erect; other bracts herbaceous, lanceolate, 2–13 mm long. Inflorescence decompound, diffuse, anthelate, of 5–80 heads, 5–25 cm tall, with branches variously erecto-patent; heads ellipsoid to obovoid, 2–6-flowered, 2–5 mm in diam. Tepals unequal, lanceolate, green to light brown, obtuse to subacute; inner tepals 2–2.8 mm long; outer tepals 1.8–2.5 mm long. Stamens 3 or 6, not exserted; anthers 0.4–0.5 mm long; filaments 0.7–1.1 mm long; style 0.4–0.6 mm long; stigmas 0.6–1 mm long. Capsules imperfectly trilocular, narrowly ovoid to obconic, acutely trigonous, acute below the c. 0.3 mm long rostrum, 2.4–3.8 mm long, castaneous to dark brown, much exceeding perianth. Seeds pale brown, 0.4–0.6 × 0.2–0.3 mm, or 0.8–0.9 mm long including appendages; appendages subequal, 0.1–0.2 mm long; outer seed coat loose, faintly striate. 2n = 80, fide N.A.Harriman & D.Redmond, Rhodora 78: 734 (1976).
E North America. 72: NBR, NSC, ONT, QUE. 74: ILL, MIN, NDA, OKL, WIS. 75: CNT, INI, MAI, MAS, MIC, NWJ, NWY, OHI, PEN, VER. 78: GEO, TEN, VRG.
72. ONTARIO: Manitoulin District, small island nr. William Island, Burnt Islands, E.C.Ogden 2413 (MO). 74. ILLINOIS: Lake Co., Dear River, Illinois Beach State Park, 1 Oct 1955, H.R.Bennett s.n. (NY). NORTH DAKOTA: Towner, 27 Jul 1913, J.Lunnell s.n. (NY). 75. INDIANA: Steuben Co., E side of Meserve Lake, C.C.Deam 52924 (BKL). MAINE: Fort Fairfield, B.L.Robinson & M.L.Fernald [Pl. Exs. Gray.] 10 (NY, WU). MICHIGAN: Washtenaw Co., 4.5 km NW of Ypsilanti, F.J.Hermann 8343 (BKL). NEW YORK: Tioga Co., Spencer Lake, Spencer, A.J.Eames & K.M.Wiegand 11744 (MO). 78. TENNESSEE: Cheatham Co., Pegram, H.K.Svenson 10549 (BKL).
Salt, brackish and calcareous marshes, poor fens, roadsides, tidal flats, swamps, patterned fen, lake shores, beaches; 0–200 m.