Discoid, floating aquatics. Root long, solitary. Thalli solitary or a few cohering, rounded to linear-lanceolate, flat or gibbous; nerves 1-5(-7). Budding pouch 1. Inflorescence of 1 female and 2 male flowers enclosed in a membranous spathe. Anther 2-thecous. Fruit 1-6-seeded. Seeds longitudinally ribbed.