Index Crit. Butom. Alism. Juncagin. 27, 44. 1868.
Herbs, perennial, to 112 cm; rhizomes not coarse; stolons absent; corms absent. Leaves submersed and emergent; petiole triangular, 11.5–35 cm; blade elliptic to ovate, 25–56 cm. Inflorescences racemes or panicles, of 4–10 whorls, emersed, 8–25 × 5–36 cm; peduncles to 76 cm; bracts connate ¼ total length, lanceolate, 4–8 mm, papillose; fruiting pedicels ascending to spreading, cylindric, 1–4.5 cm. Flowers to 3 cm diam.; sepals appressed to spreading; filaments slightly dilated, shorter than anthers, glabrous; pistillate pedicellate, without ring of sterile stamens. Fruiting heads 0.7–1 cm diam.; achenes obovoid, abaxially keeled, 1.2–1.5 × 0.7–1.1 mm, beaked; faces not tuberculate, wings 1, ± entire, glands 0–1; beak lateral, erect, 0.1–0.3 mm.
Phenology: Flowering spring–fall.
Habitat: Swamps, marshes, bogs, ditches, borders of lakes
Elevation: 0–300 m
Ark., La., Okla., Tex.