The Alismatales (alismatids) are an order of flowering plants including about 4,500 species. Plants assigned to this order are mostly tropical or aquatic. Some grow in fresh water, some in marine habitats. Perhaps the most important food crop in the order is the corm of the taro plant, Colocasia esculenta.
Hydrocharitaceae is a flowering plant family including 16 known genera with a total of ca 135 known species, that including a number of species of aquatic plant, for instance the tape-grasses, the well known Canadian waterweed, and frogbit.
The Potamogetonaceae, commonly referred to as the pondweed family, is an aquatic family of monocotyledonous flowering plants. The roughly 110 known species are divided over six genera. The largest genus in the family by far is Potamogeton, which contains about 100 species.
Zosteraceae is a family of marine perennial flowering plants found in temperate and subtropical coastal waters, with the highest diversity located around Korea and Japan. Most seagrasses complete their entire life cycle under water, having filamentous pollen especially adapted to dispersion in an aquatic environment and ribbon-like leaves that lack stomata. Seagrasses are herbaceous and have prominent creeping rhizomes. A distinctive characteristic of the family is the presence of characteristic retinacules, which are present in all species except members of Zostera subgenus Zostera.
Trochodendraceae is the only family of flowering plants in the order Trochodendrales. It comprises two extant genera, each with a single species along with up to five additional extinct genera and a number of extinct species. The living species are native to south east Asia. The two living species both have secondary xylem without vessel elements, which is quite rare in angiosperms. As the vessel-free wood suggests primitiveness, these two species have attracted much taxonomic attention.
Ruppia, also known as the widgeonweeds, ditch grasses or widgeon grass, is the only extant genus in the family Ruppiaceae, with eight 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.
Cymodoceaceae is a family of flowering plants, sometimes known as the "manatee-grass family", which includes only marine species.
Limosella is a genus of flowering plants known as mudworts. These are annual, largely aquatic plants, found in muddy areas worldwide. Its phylogeny and biogeography are inferred from molecular data
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.
Zannichellia 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.
Thalassia testudinum, commonly known as turtlegrass, is a species of marine seagrass. It forms meadows in shallow sandy or muddy locations in the Caribbean Sea and the Gulf of Mexico. Turtle grass and other seagrasses form meadows which are important habitats and feeding grounds. The grass is eaten by turtles and herbivorous fish, supports many epiphytes, and provides habitat for juvenile fish and many invertebrate taxa.
Halodule uninervis is a species of seagrass in the family Cymodoceaceae. It is native to the western Pacific and Indian Oceans. Common names include narrowleaf seagrass in English and a'shab bahriya in Arabic.
Ruppia megacarpa is a submerged herb species in the genus Ruppia found in shallow brackish waters. It is a common on Australasian coasts, including Australia (NSW; SA; Vic; WA and New Zealand. Isolated populations have been currently found in East Asia, including Japan, Korea, and Far East Russia, hence, the species distribution exhibit latitudinally disjunct distribution between East Asia and Australasia.
Ottelia is a genus of an aquatic plant family Hydrocharitaceae described as a genus in 1805. The genus is native to tropical and subtropical regions of Africa, Asia, South America, and Australia.
Althenia australis is a species of aquatic plant in the family Potamogetonaceae. It is found in fresh to brackish waters in Australia. This species has been transferred from Lepilaena.
Althenia preissii is a plant found in fresh to brackish waters in Australia. This species has been transferred from the genus Lepilaena.
Althenia marina is a plant found in brackish to marine waters in Australia. The species has been transferred from the genus Lepilaena.
Althenia bilocularis is a plant found in both Australia and New Zealand, in fresh to brackish waters. In Australia it is found in all mainland states with the exception of the Northern Territory. In New Zealand it is found on the North, South and Chatham Islands.
Althenia cylindrocarpa is a species of aquatic plant in the family Potamogetonaceae. It is found in fresh to brackish waters in Australia. This species has been transferred from Lepilaena.
Schoenus gracillimus is a species of sedge endemic to the Western Cape Province of South Africa.
