Posidonia australis
| Posidonia australis | |
|---|---|
| |
Scientific classification 
| |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Order: | Alismatales |
| Family: | Posidoniaceae |
| Genus: | Posidonia |
| Species: | P. australis
|
| Binomial name | |
| Posidonia australis | |
Posidonia australis, also known as fibre-ball weed or ribbon weed, is a species of seagrass that occurs in the southern waters of Australia. It forms large meadows important to environmental conservation. Balls of decomposing detritus from the foliage are found along nearby shore-lines.
Description
Posidonia australis is a flowering plant occurring in dense meadows, or along channels, in white sand. It is found at depths from 1–15 m (3 ft 3 in – 49 ft 3 in). Subsurface rhizomes and roots provide stability in the sands it occupies. Erect rhizomes and leaves reduce the accumulation of [[silt].
The leaves are ribbon-like and 11–20 mm (0.43–0.79 in) wide. They are bright green, perhaps becoming browned with age.[2] The terminus of the leaf is rounded or absent through damage. They are arranged in groups with older leaves on the outside, longer and differing in form from the younger leaves they surround.
The species is monoecious. The flowers appear on small spikes on leafless stems, two bracts on each spike. The plant pollinates by hydrophily, by dispersing in the water.[3]
Posidonia australis reproduction usually occurs through sexual or asexual methods but, under extreme conditions, by pseudovivipary.[4]
A 2013 study showed that P. australis can sequester carbon 35 times more efficiently than rainforests.[5]
Distribution
This species is found in waters around the southern coast of Australia. In Western Australia is occurs in the Shark Bay region, around islands of the Houtman Abrolhos, and southward along the coast of the Swan Coastal Plain. The species is recorded at the edge of the Esperance Plains, the Archipelago of the Recherche, at the southern coast of the southwest region. The range extends to the east to coastal areas of New South Wales, South Australia, Tasmania, and Victoria.[3]
A sign of a nearby occurrence of Posidonia is the presence of masses of decomposing leaves on beaches, forming fibrous balls.
Largest known plant
In June 2022 it was reported that genetic testing had revealed that samples taken from a Posidonia australis meadow in Shark Bay up to 180 kilometres (110 mi) apart had revealed that they were all from a single clone of the same plant. The plant covers an area of seafloor of around 200 square kilometres (77 sq mi), which would make it the largest known plant in the world. It is thought to be at least 4,500 years old and grew to this size by using rhizomes to colonise new parts of the seafloor.[6][7]
Taxonomy
This species is a member of the family Posidoniaceae, one of eight occurring in Australia. The ninth member, Posidonia oceanica, is found in the Mediterranean sea. The genus name for this species, Posidonia, is given for the god of the seas Poseidon, and australis refers to the southern distribution.
The species was first described by Joseph Hooker in Flora Tasmaniae.[8] Common names for the plant include fibre-ball weed and ribbon weed.[7]
Conservation status
IUCN lists this species as "near threatened",[1] while the meadows in New South Wales have been listed by the Commonwealth of Australia as an endangered ecological community since 2015.[9]
References
- ^ a b Short, F.T.; Carruthers, T.J.R.; Waycott, M.; Kendrick, G.A.; Fourqurean, J.W.; Callabine, A.; Kenworthy, W.J.; Dennison, W.C. (2010). "Posidonia australis". IUCN Red List of Threatened Species. 2010: e.T173333A6993340. doi:10.2305/IUCN.UK.2010-3.RLTS.T173333A6993340.en. Retrieved 19 November 2021.
- ^ "Posidonia australis". FloraBase. Western Australian Government Department of Biodiversity, Conservation and Attractions.
- ^ a b Mike van Keulen. "The genus Posidonia König (nom. cons.) (Posidoniaceae)". Murdoch University.
- ^ Elizabeth Sinclair. What happens when (plant) sex fails? Atlas of Science, 2016
- ^ "Humble plants may save the planet". University of Technology, Sydney. 14 August 2013. Archived from the original on 19 August 2013. Retrieved 15 August 2013.
- ^ Kilvert, Nick (1 June 2022). "World's largest plant discovered right under our noses in Western Australia". ABC News. Australian Broadcasting Corporation. Retrieved 1 June 2022.
- ^ a b Readfearn, Graham (1 June 2022). "Scientists discover 'biggest plant on Earth' off Western Australian coast". The Guardian. Retrieved 1 June 2022.
- ^ Hooker, J.D. (1858). "The botany of the Antarctic voyage of H.M. discovery ships Erebus and Terror . III. Flora Tasmaniae". 2 (6): 43.
{{cite journal}}: Cite journal requires|journal=(help) - ^ Australian Government. "Species Profile and Threats Database: Posidonia australis seagrass meadows of the Manning-Hawkesbury ecoregion". Department of Agriculture, Water and the Environment.
External links
- Posidonia australis occurrence data from Australasian Virtual Herbarium
- "Posidonia australis". Australian Plant Name Index (APNI), IBIS database. Centre for Plant Biodiversity Research, Australian Government.
- "Posidonia australis Growing in Altered Salinities: Leaf Growth, Regulation of Turgor and the Development of Osmotic Gradients". CSIRO.