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 APG system (1998) and APG II system (2003) accept this genus as constituting the sole genus in the family Posidoniaceae, which it places in the order Alismatales, in the clade monocots.
The AP-WebsiteAP-Website concludes that the three families Cymodoceaceae, Posidoniaceae and Ruppiaceae form a monophyletic group.
Earlier systems classified this genus in the family Potamogetonaceae or in the family Posidoniaceae but belonging to order Zosterales.
Posidonia oceanica has nitrogen fixation capabilities via symbiosis and other species may as well.
Species
This is a list of species that are contained by the genus:
Posidonia angustifolia Cambridge and KuoCambridge, M.L. and Kuo, J. (1979)
Two new species of seagrass from Australia, Posidonia sinuosa and Posidonia angustifolia (Posidoniaceae).
Aquat.
Bot.
6, 307–328 f.
Keulen
Posidonia australis Hook.f. South coast of Australia.
Posidonia coriacea Cambridge and Kuo
Posidonia denhartogii Kuo and CambridgeKuo, J. and Cambridge, M.L. (1984)
A taxonomic study of the Posidonia ostenfeldii complex (Posidoniaceae) with descriptions of four new Australian seagrasses.
Aquat.
Bot.
20, 267–95.
f. Keulen
Posidonia kirkmanii Kuo and Cambridge
Posidonia oceanica (L.) Delile – This plant is endemic to the Mediterranean Sea, where it forms undersea meadows.
Posidonia ostenfeldii den Hartogden Hartog, C. (1970) Seagrasses of the World.
Verh.
Kon.
Ned.
Akad.
Wetens.
Afd.
Naturk.
Ser.
2 59:139 f.
Keulen
Posidonia robertsoniae Kuo and Cambridge
Posidonia sinuosa Cambridge and Kuo
The species described by Linnaeus, Posidonia oceanica, is found in the Mediterranean; the rest are located around the southern coast of Australia.
Some species are endemic seagrasses of Western Australia, all the Australian species are found in that region's diverse habitats.
This arrangement was divided into two complexes: the Posidonia australis and Posidonia ostenfeldii groups.Kuo, J. and McComb, A.J. (1989)
In: "Biology of Seagrasses.
A treatise on the biology of seagrasses with special reference to the Australian region." (Eds. A.W.D. Larkum, A.J. McComb, S.A. Shepherd) (Aquatic Plant Studies 2)
(Elsevier, Amsteredam).
p. 6-73 f.
Keulen Some species descriptions may only be regional characteristics, and may need further revision.
In 2006 a clonal colony of P. oceanica was discovered south of the island of Ibiza which measured 8 km across and possibly up to 100,000 years old.
Taxonomy
References
External links
Posidoniaceae in L. Watson and M. J. Dallwitz (1992 onwards) The families of flowering plants.
Flora Europaea: Posidonia
