Alismataceae

About 12 genera and 81 species (mainly northern hemisphere in tropics and subtropics), with four genera and four species indigenous to southern Africa. In addition, there is one genus and species naturalised, and two genera and two species cultivated in southern Africa. Aquatic or marsh herbs.

Aponogetonaceae (Wateruintjie family)

There is only one genus, Aponogeton, in this family. There are 43 species, occurring in tropical to temperate regions of Asia, Africa, Madagascar and Australia. Six species occur in Southern Africa. Plants grow in freshwater with leaves floating on the surface. 

Araceae (Arum lily family)

There are 106 genera and about 4025 species (tropics and subtropics plus some species in temperate regions; especially diverse in New World tropics), with nine genera and 21 species indigenous to southern Africa. In addition one genus and one species is naturalised, and 18 genera and 44 species are cultivated in the region. The Lemnaceae has been synonymised with the Araceae and previous members of this family are included here. They are all aquatic plants with small floating leaves and tiny flowers. 

Cymodoceaceae

Submerged, perennial marine plants. There are five genera and 16 species (tropical seas, with two genera and two species in off southern Africa (seas along the eastern coast).

Hydrocharitaceae

Freshwater or marine herbs. There are 18 genera and about 116 species (cosmopolitan), of which four genera and 11 species are indigenous to southern Africa and one genus with one species is naturalised.

Juncaginaceae

Marsh-inhabiting plants. There are four genera and 15 species (cosmopolitan), with one genus, Triglochin, and two species indigenous to southern Africa.

Limnocharitaceae

Aquatic plants, either rooted or free-floating. Three genera and 11 species worldwide, with one species, Butomopsis latifolia, indigenous to southern Africa (Okavango delta, Botswana). In addition, the Water poppy Hydrocleys nymphoides is cultivated in southern Africa.

Potamogetonaceae (pondweed family)

Floating, aquatic plants. Four genera and about 102 species worldwide, of which one genus, Potamogeton, is indigenous in southern Africa, represented by seven species.

Ruppiaceae

Aquatic, grass-like, herbs that grow in saline or fresh water. Ruppia is the only genus in the family, and contains about seven species of which two are indigenous in southern Africa.

Zosteraceae (eel grass family)

Marine perennial plants that form large beds along coastal areas, mainly in temperate regions and typically occurring in estuaries . There are two genera and 14 species, of which one species, Zostera capensis, occurs in southern Africa.