Rhizomes branched or unbranched, erect, ovoid; stolons slender. Leaves: petiole sparsely to densely puberulent. Leaf blade abaxially purplish, adaxially green, nearly orbiculate, to ca. 3 × 3 dm, margins spinose-dentate; venation radiate and prominent centrally, without weblike pattern, principal veins ca. 15; surfaces abaxially sparsely to densely puberulent. Flowers emersed, 12-25 cm diam., opening nocturnally, many flowers not closing until late morning, only sepals and outermost petals in distinct whorls of 4; sepals abaxially uniformly green, prominently veined, lines of insertion on receptacle not prominent; petals 16-20, white; stamens ca. 75, yellow, outer with connective appendage projecting less than 2 mm beyond anther; filaments widest below middle, slightly shorter to longer than anthers; pistil ca. 20(-30)-locular, appendages at margin of stigmatic disk linear, 6-12 mm. Seeds ellipsoid, 1.4-1.8 × 0.9-1.2 mm, ca. 1.5-1.6 times as long as broad, with longitudinal ridges bearing papillae 20-150 µm. Flowering spring-summer. Ponds, ditches, and canals; 0-100 m; introduced; Fla., La.; Africa.