Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families, all in the order Alismatales. Seagrasses evolved from terrestrial plants which recolonised the ocean 70 to 100 million years ago.
Zostera is a small genus of widely distributed seagrasses, commonly called marine eelgrass, or simply seagrass or eelgrass, and also known as seaweed by some fishermen and recreational boaters including yachtsmen. The genus Zostera contains 15 species.
A seagrass meadow or seagrass bed is an underwater ecosystem formed by seagrasses. Seagrasses are marine (saltwater) plants found in shallow coastal waters and in the brackish waters of estuaries. Seagrasses are flowering plants with stems and long green, grass-like leaves. They produce seeds and pollen and have roots and rhizomes which anchor them in seafloor sand.
Halophila johnsonii, or Johnson's seagrass, is a small, asexual seagrass in the family Hydrocharitaceae. It occurs only on the southeastern coast of Florida, and was the first marine plant listed on the United States endangered species list, though it was removed from listing in April 2022. Female flowers have been observed, but even with decade long observational studies, neither male flowers nor seed have ever been observed.
Amphibolis antarctica is a species of flowering plant in the family Cymodoceaceae. It is referred to by the common names wire weed or sea nymph, and is a seagrass found in coastal waters of southern and western Australia.
Halophila is a genus of seagrasses in the family Hydrocharitaceae, the tape-grasses. It was described as a genus in 1806. The number of its contained species, and its own placement in the order Alismatales, has evolved.
The Seagrasses of Western Australia are submerged flowering plants found along the coast, around islands, and in Estuaries of Western Australia. The region contains some of the largest seagrass meadows in the world, and is the most diverse in the number of species. The variety of habitats along its western and southern coasts is often soft sands in shallow subtropical waters, ideal for these plants.
Enhalus is a monotypic genus of marine flowering plants. The sole species is Enhalus acoroides. Enhalus is a large seagrass native to coastal waters of the tropical Indian and Western Pacific Oceans. It is the only species of seagrass that does aerial surface pollination in which the pollen and the styles remain dry. Enhalus is surface pollinated with male flowers that detach from the plant to float on the surface until they reach a female flower where pollination can occur. Enhalus acoroides is considered a slow-growing, "climax" species.
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.
Zostera marina is a flowering vascular plant species as one of many kinds of seagrass, with this species known primarily by the English name of eelgrass with seawrack much less used, and refers to the plant after breaking loose from the submerged wetland soil, and drifting free with ocean current and waves to a coast seashore. It is a saline soft-sediment submerged plant native to marine environments on the coastlines of northern latitudes from subtropical to subpolar regions of North America and Eurasia.
Cymodocea nodosa is a species of seagrass in the family Cymodoceaceae and is sometimes known as little Neptune grass. As a seagrass, it is restricted to growing underwater and is found in shallow parts of the Mediterranean Sea and certain adjoining areas of the Atlantic Ocean.
Halophila engelmannii is a species of seagrass in the Hydrocharitaceae family. It is referred to by the common names star grass and Engelmann's seagrass and grows underwater on shallow sandy or muddy sea floors. It is native to the Bahamas, the Cayman Islands, Costa Rica, Cuba, the Gulf Coast of the United States, the Gulf Coast of Mexico, Puerto Rico, and Trinidad and Tobago.
Halophila decipiens, commonly known as Caribbean seagrass or paddle grass, is a seagrass in the family Hydrocharitaceae. It grows underwater on sandy or muddy sea floors in shallow parts of tropical seas.
Halodule wrightii is an aquatic plant in the Cymodoceaceae family. It is referred to by the common names shoal grass or shoalweed, and is a plant species native to seacoasts of some of the warmer oceans of the world.
Zostera noltii is a species of seagrass known by the common name dwarf eelgrass. It is found in shallow coastal waters in north western Europe, the Mediterranean Sea, Black Sea, Caspian Sea and Aral Sea and on islands in the Atlantic off the coast of northwest Africa. It is an important part of the intertidal and shallow subtidal ecosystems of estuaries, bays and lagoons.
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.
Zostera novazelandica Setchell is a species of seagrass in the family Zosteraceae found on the shores of New Zealand. It is regarded as a distinct species by some authors but considered as a synonym of Zostera muelleri Irmisch ex Ascherson by others. The Maori names for Zostera novazelandica are karepō, nana, rehia, and rimurehia.
Zostera capricorni is a species of eelgrass in the Zosteraceae family. It is native to the seacoasts of New Guinea, Queensland, New South Wales, Victoria, South Australia, Norfolk Island and the North Island of New Zealand. It was first discovered at Moreton Bay in Queensland in 1875.
Syringodium isoetifolium, commonly known as noodle seagrass, is a species of flowering plant in the family Cymodoceaceae, growing underwater in marine habitats. It forms seagrass meadows in shallow sandy or muddy locations in the Indian and Pacific Oceans.
Posidonia australis seagrass meadows of the Manning-Hawkesbury ecoregion is an endangered ecological community, listed under the EPBC Act of the Commonwealth of Australia on 7 May 2015
