Herbs, perennial, cespitose, (10--)15--70(--90) cm, base not bulbous. Stems compact. Leaves in narrow to broad fans, 5--50 cm; sheaths soft, base reddish; blade deep green, linear to linear---sword-shaped, flat, not twisted, under 7 mm wide, papillate or smooth, margins smooth or papillate, somewhat scabrous. Inflorescences: scape sheaths exceeded by leaves; scapes linear to filiform, terete proximally, terete or ancipital-2-edged--winged distally, 0.5--3 mm wide, variably ribbed, distally with 3 or more somewhat scabrous ribs, ribs papillate to scabrous; spikes prevalently ovoid, 5--20 mm, apex usually acute; fertile bracts (4--)5--7(--9) mm, margins entire, apex rounded. Flowers: lateral sepals included, slightly curved, 5--7 mm, keel brown, scarious, lacerate; petals unfolding in morning, blade obtriangular, 4 mm; staminodes bearded. Seeds translucent to mealy, ovoid to ellipsoid, 0.5 mm, finely lined longitudinally with small papillae.
Lvs broadly linear or elliptic-linear, mostly 10-50 cm נ5-15 mm, spreading, lustrous dark green, anthocyanic at the dilated, soft, thin, keeled base; scapes 1.5-7 dm, terete and twisted below, straighter above and somewhat compressed, with 2 broad thin ridges that may be collectively as wide as the body; spikes 0.5-1.5 cm at maturity, ovoid to subglobose, blunt or acute; lateral sep shortly included, the broad keel lacerate in its upper half; pet-blades cuneate, 4 mm, yellow, unfolding in the morning; seeds 0.5-0.6 mm, broadly ellipsoid, very finely ribbed; 2n=18. Wet, low, often sandy places, often in river-swamps; coastal region from s. Me. to Fla. and Tex., and less commonly inland to Mich., Ind., Wis., and Okla. Midsummer-fall. Two vars. with us, both widespread. Var. difformis is ±robust, with smooth lvs. Var. curtissii (Malme) Kral is smaller and more tufted, seldom over 2 dm, the lf-surfaces evidently papillate. (X. bayardii; X. curtissii; X. papillosa)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.