Origin: Introduced from eastern North America
Conservation Status: Not of concern
Herbaceous perennials to 100 cm, with coarse rhizomes, stolons and corms absent.
Submersed or emersed, margins entire; leaves under water phyllodial, angled beneath and flattened above, 6.4-35 cm long and 0.5-4 cm broad; leaves above water petiolate, petioles triangular and 6.5-17 cm long, blade linear to linear-oblanceolate, 2.5-17.5 cm long and 0.2-4 cm broad.
Inflorescences bracteate racemes or panicles with 1-12 whorls, above water, 2.5-21 cm long and 1-8 cm broad; peduncles 6.5-29.7 cm long; bracts connate greater than or equal to ¼ total length, broadly subulate to lanceolate, 20-50 mm, not papillose; fruiting pedicels spreading and cylindric to 5 cm; flowers imperfect, to 2.3 cm in diameter; sepals 3, curving backward to spreading, not encasing the flower; petals 3, white, deciduous; filaments widened, shorter than anthers, pubescent; anthers 2 chambered, splitting longitudinally; pistillate flowers pedicellate, sterile stamens absent.
Fruiting heads 0.6-1.5 cm in diameter; achenes oblanceoloid with no abaxial keel, 1.5-2.8 mm long and 1.1-1.5 mm broad, beaked; faces not forming any projections or protuberances, abaxial wings absent or 1, entire, glands 1 or 2; beak lateral and erect, 0.2 mm.