C. H.Ostenfeld: Contributions to West Australian Botany. I. 33 



split into 2 — 3 lobes, and the whole pericarp was spread out as 

 a nearly flat body, thus liberating the seedling which had drop- 

 ped out. These empty pericarps were present in great masses on 

 the shore, and were also to be seen in immense numbers float- 

 ing in the water. Amongst the empty pericarps I found several 

 whole fruits which had just begun to open; they are oblique- 

 ovoid in shape and each contains a large green seedling. Unope- 

 ned fruits were also found, some unripe or barren. Evidently 

 Posidonia liberates its fruits when ripe, and owing to presence of 

 air in the tissues of the pericarps they rise to the surface and 

 float. Then they open and the seedling, which is heavier than 

 Water, drops out and sinks to the bottom while the pericarp 

 continues to float for a time and 

 then breaks up." 



,,The thousands of pale green 

 or yellowish green open pericarps, 

 form, together with the leaves, a 

 fringe along the shore, and present 

 a peculiar sight". 



A later examination of the 



material collected and of further £ig. 18. Posidonia australis, from 



„ . . ... Carnarvon. 1 ransverse section of a 



specimens from South Australia has leaf-blade. The thick walls of the 



added to my notes and allows epidermis and the selerenchyma- 



. ii-,- strands are shown in black, the 



me to make some additions to ve i n (one of the lateral veins) is 



the descriptions of the species as shaded, x, lacunæ. (About i 5 "/i 



„ nat. size. 

 given in floras. 



The creeping rhizome is short-jointed, and in the axil of 

 each leaf there is a short erect shoot with densely arranged lea- 

 ves. As in the Mediterranean species, the leaf-sheath (8 — 12 cm 

 long) persists for some time after the shedding of the lamina; 

 the old sheaths split into fine filaments consisting of the scle- 

 renchyma-strands. Thus the erect shoots become enveloped at 

 their base in a cover of these filamentous remains, but hardly 

 to such an extreme degree as is the case with P. oceanica. The 

 leaf-blades are long (up to 65 cm measured) and ribbon-like (5 — 

 14, generally 8 — 10, mm broad) with a truncate apex and entire 

 margins. Their structure is known by the investigations of C. 

 Sauvageau (1. c, 1890), and an examination of my material con- 

 firms his description. In a transverse section (Fig. 18) the charac- 

 teristic points are : a small-celled and thick-walled epidermis ; 

 numerous small sub-epidermal sclerenchyma-strands, a lacunose 

 mesophyll with septa formed by several cells, and scattered small 



Dansk Botanisk Arkiv, Bd. 2. Nr. 6 3 



