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.
The dicotyledons, also known as dicots, are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, that the seed has two embryonic leaves or cotyledons. There are around 200,000 species within this group. The other group of flowering plants were called monocotyledons, typically each having one cotyledon. Historically, these two groups formed the two divisions of the flowering plants.
Petals are modified leaves that surround the reproductive parts of flowers. They are often brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the corolla. Petals are usually accompanied by another set of modified leaves called sepals, that collectively form the calyx and lie just beneath the corolla. The calyx and the corolla together make up the perianth, the non-reproductive portion of a flower. When the petals and sepals of a flower are difficult to distinguish, they are collectively called tepals. Examples of plants in which the term tepal is appropriate include genera such as Aloe and Tulipa. Conversely, genera such as Rosa and Phaseolus have well-distinguished sepals and petals. When the undifferentiated tepals resemble petals, they are referred to as "petaloid", as in petaloid monocots, orders of monocots with brightly colored tepals. Since they include Liliales, an alternative name is lilioid monocots.
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.
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.
Commelinaceae is a family of flowering plants. In less formal contexts, the group is referred to as the dayflower family or spiderwort family. It is one of five families in the order Commelinales and by far the largest of these with about 731 known species in 41 genera. Well known genera include Commelina (dayflowers) and Tradescantia (spiderworts). The family is diverse in both the Old World tropics and the New World tropics, with some genera present in both. The variation in morphology, especially that of the flower and inflorescence, is considered to be exceptionally high amongst the angiosperms.
Schisandraceae is a family of flowering plants with 3 known genera and a total of 92 known species. Such a family has been recognized by most taxonomists, at least for the past several decades. Before that, the plants concerned were assigned to family Magnoliaceae and Illiciaceae.
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.
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.
Asteliaceae is a family of flowering plants, placed in the order Asparagales of the monocots.
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.
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.
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.
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.
Thalassodendron ciliatum, the sickle-leaved cymodocea, is a species of plant in the Thalassodendron genus of seagrasses in the family Cymodoceaceae.
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.
