Aquatic, mostly perennial herbs. Leaves submerged, floating or emergent, alternate, opposite or whorled, often sheathing, margins sometimes prickly. Flowers mostly unisexual, more or less regular, solitary or in few-flowered clusters mostly with a spathe of 2 united bracts, submerged, floating or emergent. Sepals and petals usually 3. Stamens 2-many in 1-many whorls, male flowers sometimes shed to float on the surface. Ovary inferior. Carpels 3-6, united, containing numerous ovules. Fruit a septicidal berry-like capsule that opens irregularly.

Frequently grown in aquaria and a few as pond or marginal plants; several species are extremely weedy, such as Elodea canadensis in Europe and Lagarosiphon in New Zealand.

Probably most closely related to Butomaceae.

15 genera and about 115 species both marine and freshwater, cosmopolitan but mainly tropical.Australia has 9 native genera with about 20 species.

Aquatic herbs; flowers differentiated into sepals and petals, subtended by a spathe or spathe-like pair of bracts; ovary inferior; fruit berry-like.

Source: Spencer, R. (2005). Hydrocharitaceae. In: Spencer, R.. Horticultural Flora of South-eastern Australia. Volume 5. Flowering plants. Monocotyledons. The identification of garden and cultivated plants. University of New South Wales Press.