Herbs, perennial, rhizomatous, sometimes to nearly cespitose, 4--10 dm. Rhizomes not tuberous, 2 mm diam. Culms erect, terete, 3--5 mm diam., smooth. Cataphylls 0. Leaves: basal 2--3(--6), cauline 1--4; auricles 1--3 mm, apex acute, membranaceous, absent on proximal leaves; blade green, laterally compressed, 9--70 cm x 2--6 mm. Inflorescences terminal panicles of 10--30 heads, 10--30 cm, branches spreading; primary bract erect; heads 20--30-flowered, spheric, (10--)12--15 mm diam. Flowers: tepals green to reddish, lance-subulate, 4--5 mm, apex acuminate; stamens 3, anthers 1/3--1/2 filament length. Capsules exserted, straw-colored, 1-locular, subulate, 4--5,5 mm, tapering to subulate tip, valves separating or not at dehiscence; fertile throughout or only proximal to middle.. Seeds broadly ellipsoid, 0.5--0.6 mm, not tailed; body clear yellow-brown.

Stems stout and tough, clustered, 3-10 dm; lvs aerenchymatously hollow and transversely evidently septate, but also flattened and ±equitant, basal and cauline, the basal ones 1-5 dm נ3-6(-8) mm; cauline lvs 3-several, well spaced, the lower like the basal, the upper smaller; infl terminal, well surpassing the invol bracts, these mostly 1-8 cm; heads mostly 15-75, often individually sessile on the ±elongate branches, hemispheric to subglobose, many-fld, 7-15 mm thick; fls eprophyllate; sep green to brownish-stramineous, rigid, slender, gradually tapering, 3.5-4.5 mm, the pet similar but a bit shorter; stamens 3, included; fr slender, trigonous-subulate, unilocular, surpassing the sep by 1-2 mm; seeds rather few, plump, 0.3-0.4 mm. Wet places, as along ditches, streams, and ponds; se. Va. to Fla. and Tex., and inland to w. Tenn., Mo., and Okla.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

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