Skip to main content

Service Notice

The Western Australian Herbarium’s collections management system, WAHerb, and DBCA’s taxonomic names application, WACensus, have been set to read-only mode since 1 October 2025. Recent taxonomic changes are not reflected in Florabase, herbarium collections, or in the census. We are hoping to be able to reinstate services around December 15; we will provide an update at that time.

The notice period started at 9:00 am on Wednesday, 1 October 2025 +08:00 and will end at 12:00 pm on Monday, 15 December 2025 +08:00.

Advanced Search

Posidoniaceae Vines

Reference
Stud.Text-Book Bot. p553 (1895)
Name Status
Current

Scientific Description

Common name. Posidonia Family.

Habit and leaf form. Marine herbs. Perennial. Young stems flattened. Rhizomatous. Hydrophytic; marine; rooted. Leaves submerged; medium-sized; alternate; distichous; sessile; sheathing. Leaf sheaths with free margins. Leaves simple. Leaf blades entire; flat, or solid; linear; one-veined, or parallel-veined; without cross-venules. Leaves ligulate. Axillary scales present. Leaf blade margins entire, or serrate. Stem anatomy. Secondary thickening absent.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Pollinated by water.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’. The terminal inflorescence unit cymose, or racemose (hard to determine). Inflorescences scapiflorous; clusters of spikelike inflorescences, each with three to five flowers, each ‘spike’ terminated by a flower. Flowers minute. Perianth absent. Androecium 3. Androecial members all equal; free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 3; with sessile anthers (the two thecae borne dorsally near the midvein at the base of a broad, shieldlike connective). Anthers dehiscing via longitudinal slits; extrorse; bilocular; tetrasporangiate (the thecae widely separated); appendaged (in that the connective has an apically prolonged midrib). Pollen shed as single grains. Pollen grains lacking exine, and dispersed in the sea as long filaments. Gynoecium seemingly 1 carpelled. The pistil 1 celled. Gynoecium monomerous; of one carpel; superior. Carpel non-stylate (irregularly many-lobed); apically stigmatic; 1 ovuled. Placentation apical. Ovules pendulous; orthotropous.

Fruit and seed features. Fruit somewhat fleshy (the pericarp spongy). The fruiting carpel dehiscent. Seeds non-endospermic. Cotyledons 1. Embryo straight.

Geography, cytology, number of species. World distribution: coastal Mediterranean and southern Australia. 3 species.