Alismatales genera

Potamogeton is a genus of aquatic, mostly freshwater, plants of the family Potamogetonaceae. Most are known by the common name pondweed, although many unrelated plants may be called pondweed, such as Canadian pondweed (Elodea canadensis). The genus name means "river neighbor", originating from the Greek potamos (river) and geiton (neighbor).

thumb|right|Zostera sp in Mussel Ridge Channel, Birch Island, Maine

thumb|right|Ruppia polycarpa Ruppia, also known as the widgeonweeds, ditch grasses or widgeon grass, is the only extant genus in the family Ruppiaceae, with 11 known species. These are aquatic plants widespread over much of the world. The genus name honours Heinrich Bernhard Rupp, a German botanist (1688–1719). They are widespread outside of frigid zones and the tropics.

Zannichellia (common name horned pondweed) is a genus of submerged aquatic flowering plant, with threadlike leaves and tiny flowers. It is fully adapted to an aquatic life cycle, including underwater pollination.

Posidonia is a genus of flowering plants. It contains nine species of marine plants ("seagrass"), found in the seas of the Mediterranean and around the south coast of Australia.

Triglochin is a plant genus in the family Juncaginaceae described by Carl Linnaeus in 1753. It includes 25 known species. It is very nearly cosmopolitan in distribution, with species on every continent except Antarctica. North America has four accepted species, two of which can also be found in Europe: Triglochin palustris (marsh arrowgrass) and Triglochin maritima (sea arrowgrass). Australia has many more.

The Aponogetonaceae (the Cape-pondweed family or aponogeton family) are a family of flowering plants in the order Alismatales.

Tofieldia is a small genus of flowering plants described as a genus in 1778. It is widespread across much of Europe, Asia, and North America.

Stuckenia is a genus of flowering aquatic plants. It contains approximately 30 species that grow in shallow water. Pondweed is a common name for plants in this genus.

Amphibolis is a genus in the family Cymodoceaceae. It includes two species of sea grass endemic to the western and southern coast of Australia, Amphibolis antarctica and Amphibolis griffithii, commonly known as sea nymph or wire weed.

thumb|Phyllospadix is a food source for many animals including this Tectura palacea.

Syringodium is a genus in the family Cymodoceaceae described as a genus in 1860. It is found along shorelines of tropical and subtropical marine environments (Indian and Pacific Oceans, Caribbean, Gulf of Mexico).

Cymodocea is a genus in the family Cymodoceaceae described as a genus in 1805. It includes three species of sea grass distributed in warm oceans.

thumb|right|Lepilaena australis Harv., 1855 Althenia is a genus of aquatic plants of the family Potamogetonaceae. This has long been a group of two species in the Mediterranean Europe and South Africa, but in 2016 was revised to include an Australasian relative, Lepilaena. The genus is named after the agronomist Jean Althen.

Halodule is a genus of plants in the family Cymodoceaceae described as a genus in 1841. It is widespread on tropical and semi-tropical ocean shores of all continents except Europe and Antarctica.

Thalassodendron is a genus of seagrass in the family Cymodoceaceae, described as a genus in 1970. It grows along the shores of the Indian Ocean, the western Pacific Ocean and around Australasia.

Harperocallis is a genus of flowering plants in the family Tofieldiaceae, native to Florida and northwestern South America. It was originally described as a monotypic genus, based on the Floridian H. flava, in 1968, but was expanded in 2013 to include ten South American species formerly placed in Isidrogalvia.

Cycnogeton is a genus of plants in the family Juncaginaceae described as a genus in 1838. It is native to Australia and New Guinea.