At least 5 species, 4 restricted to temperate waters of Australia, 1 to the Mediterranean region; 1 species in Victoria. 'Posidonia balls' or 'marine balls' which are commonly found on southern Australian shores are formed principally of detrital remains of P. australis, as well as fragments of other seagrasses, algae and shells.
Source:
Conn, B.J. (1994). Posidoniaceae. In: Walsh, N.G.; Entwisle, T.J., Flora of Victoria Vol. 2, Ferns and Allied Plants, Conifers and Monocotyledons, pp. 160–161. Inkata Press, Melbourne.
