C. H. Ostenfeld: Contributions to West Australian Botany. I. 31 



5. Posidonia australis J. D. Hooker, 



Flor. Tasman. II (1860) 43; F. v. Müller, Fragm. Phytog. Austr. VIII 

 (1872—74) 218; Sec. Census (1889) 204; Bentham, Fl. Austr. VII (1878) 175; 

 Ascherson, in Das Pflanzenreich IV 11 (1907) 38; Caulinia oceanica R. Brown, 

 Prodr. Nov. Holl. I (1810) 339; C. australiana F. v. Müller, Fragm. Phytogr. 

 Austr. VI (1868) 198. 



Next to Cymodocea antarctica this species is the most com- 

 mon sea-grass along the coast of West Australia. It is known 

 from several places between King George's Sound and Sharks Bay. 



Outside West Australia it occurs on the coasts of South 

 Australia, Victoria and Tasmania, that is along the whole south- 

 ern side of the continent, and extending further to the extra- 

 tropical west coast. 



It has only one congener, P. oceanica (L.) Del., an inhabit- 

 ant of the Mediterranean. The genus which stands very isolated 

 within the family, is evidently a very old type, and the restric- 

 ted and discontinuous areas of the two species point to a much 

 wider distribution in former times. 



We know the morphology, the structure and the biology of 

 the Mediterranean species comparatively well through investiga- 

 tions by French and Italian scientists 1 . In general the Austra- 

 lian species seems to be similar, but as far as I have seen, little 

 has been written about it, and as I found the plant in fruit and 

 observed the dispersal of the fruits, I think it worth while to 

 publish my observations. Both at Geraldton (No. 269) and at 

 Carnarvon (No. 268) the fruits and leaves of the plant were cast 

 ashore in quantities (28th and 31st Octob. 1914). The following 

 is an extract from my note-book regarding this phenomenon, as 

 it was observed at Geraldton: 



"The fringe of cast-up material on the coast at Geraldton 

 consisted mostly of Posidonia australis. Besides leaves — both 

 foliage leaves and the short involucral leaves of the inflorescence 

 — the material included numerous fruits of this plant. Most of 

 them had opened. The basal part of the fleshy pericarp had 



1 Ph. Caulinus,: Zosteræ oceanicæ Linnei anthesis, Neapoli, 1792. 

 Germain de Saint-Pierre, in Bull. Soc. bot. de France IV (1857) 



575, et VII (1860) 474. 

 Ch. Grenier, ibid. VII (1860) 362, 419, 448. 

 Ad. Brongniart et Arthur Gris, ibid VII (1860) 472. 

 Ch. Flahallt. in Kirchner, Loew u. Schroeter, Lebensgesch. der Blü- 



tenpfl. Mitteleurop. vol. I, 1 Abt. (1908) 537. 

 C. Sauvageau, in Journ. de Botanique IV (1890) 221, 237, et VII 



(1893) 95. 



