Rhizomes green, extensively branched, forming large clumps, 2-4 cm diam., with pale leaf scars. Stems 2-3-branched, solid, 10-15(-20+) dm. Leaves: basal 4-6, erect, blade bright green, ensiform, 10-13 dm × 2-3 cm, apex slightly curved; cauline with blade foliaceous, appearing as elongated spathe, 5-6.5 dm × 2-3 cm, not exceeding flowers. Inflorescence units 2-3-flowered, branch units 1-2-flowered; spathes tightly enclosing ovary and pedicel, 15-20 cm, subequal; outer narrowly lanceolate, keeled, margins pale, narrow, inner margins translucent, broad, scarious. Flowers: perianth blue or blue-purple; floral tube tubular-prismatic, 9-ribbed and -grooved, 4-5 cm; sepals blue or blue-purple with white streaks surrounding signal, oval to orbicular-oval, 9.5-11 × 4-5 cm, base abruptly attenuate into claw, apex obtusely angled, signal with raised, yellow, pubescent central ridge, claw green, striate, 4-4.5 × 1-1.2 cm; petals erect or spreading-erect, spatulate, 7-8.5 × 2-3 cm, base cuneate, apex emarginate; ovary bluntly 6-angled, 4-4.5 cm; style blue-violet, keeled, 3.5-4 cm, raised above sepals, crests recurved, 1.5-2 cm, margins sharply and irregularly serrate; stigmas 2-lobed with 2 triangular teeth; pedicel columnar, 3.5-5 cm. Capsules drooping, bright green, ellipsoid, hexagonal in cross section, with 6 broad, rounded lobes, 8-10 × 3 cm, indehiscent; after anthesis, flower stem elongates, arching downward to push capsule into water, where walls are broken down and as funiculus is broken, seed rises to surface. Seeds in 2 rows per locule, brown, D-shaped, 8-10 mm wide, very corky. 2n = 44. Flowering Mar--Apr. Shallow water or very wet roadside ditches; Ala., La., Miss.