Description: Dioecious aquatic perennials with submerged leaves and floating flowers.
Leaves mostly whorled.
Inflorescences unisexual, axillary. Flowers with 2 perianth whorls, segments ± equal in size. Male flowers solitary, separating when in bud and rising to the surface, opening when free-floating; spathe sessile in leaf axils; hypanthium absent in male flowers, thread-like in female flowers; stamens 3. Female flowers solitary; ovary 1-locular; styles 3.
Fruit ± cylindrical, seeds 2–6.
Distribution and occurrence: World: 1 species, Australia, Africa & Asia. Australia: 1 species (native).
Text by S. W. L. Jacobs