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Learn more about native seagrass habitats, habits and structures.

Halophila ovalis, commonly known as paddle weed, spoon grass or dugong grass, is a seagrass in the family Hydrocharitaceae. It is a small herbaceous plant that occurs in sea beds and other saltwater environments in the Indo-Pacific.

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The plant occurs around reefs, estuaries, islands, inter-tidal areas, on soft sand or mud substrates. The leaves are ovate in outline, appearing on stems that emerge from rhizome beneath the sand. The roots get up to 800 mm long and covered in fine root hairs. It is often found in meadows that dominate a sand bank or other patch of sea floor. The arrangement of the plant, above and below ground, provides stability to the sea floor and habitat for other species.

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It is used as food by dugong, as is therefore known as dugong grass.

Halophila Minor has small leaves, approximately 0.7-1.2 mm in width.

 

Leaves became a set from two pieces that rise up from the rhizomes, and they are oval to elliptical, with every 6-10 veins given off toward right and left margins from the longitudinal vein.

This species is found on muddy substrate in subtidal zones, and in deeper places along shorelines with calm water movement.

Beccari's seagrass has small leaves, the smallest just got 0.5cm long. 

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The long oval-shaped leaves emerge in a rosette of 5-10 tiny leaves on long thin stems. Each plant may bear both male and female flowers, but usually, only male or female flowers are visible on a plant. The flowers and fruits are tiny. Each fruit contains up to 6 seeds.

Widgeon grass has delicate, thread-like leaves with rounded tips and a sheath at the base. Leaves grow alternately along slender, branching stems. The grass grows in two forms: an upright, branched form with flowers that stand several feet tall, and a short, creeping form with leaves at the base of the plant.

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In late summer, long stalks with clusters of individual black, pointed seeds grow from the base of the leaves. Widgeon grass has an extensive root system with creeping rhizomes (underwater portion of a plant's stem) that lack tubers which are a specialzed stem or root organ that stores nurtrients.

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Widgeon grass reproduces sexually between late spring and late summer when two flowers, which are enclosed in a sheath at the base of the leaves, emerge and grow on a stalk toward the water’s surface. Pollen floating on the water’s surface fertilizes the flowers, which then produce seeds. It can also reproduce asexually, when new stems grow from the plant’s root and rhizome system.

Dwarf Eel Grass has a creeping rhizome that runs along under the surface of the seabed. Groups of two to five strap-shaped leaves grow out of nodes on the rhizome and each node also bears a tuft of up to four short roots that anchor the plant in the sediment. The leaves have three irregular, longitudinal veins and blunt, notched ends. They are up to 22 cm long and contain air spaces which make them buoyant. Several separate male and female flowers grow on a short, spear- shaped lateral stem. The smooth white seeds develop inside a green capsule with membraneous walls and are about 2 mm long.

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Zostera noltii grows intertidally on fine sandy or muddy substrates and can tolerate various levels of salinity and often mixed with other seagrasses. It grows subtidally in deeper water when it is in low salinity or brackish water in estuaries and lagoons.