C. H.Ostenfeld: Contributions to West Australian Botany. I. 35 



as in fig. 12 D of "Das Pflanzenreich", IV 11, p. 37); they differ 

 considerably from the connectives of P. oceanica which are broadly 

 obovate-cordate with a long mucro and as a rule are denticulate 

 at the base of the mucro. On their outer face there is a keel 

 on which the pollen sacs were placed, but these are thrown off 

 after flowering (Fig. 21a). The base of the fruit is fringed by the 

 persistent connectives as by a cup-shaped perianth (Fig. 20). 



The female organ consists of one sessile carpel terminating 

 in a sessile stigma which is said to be lobed (F. v. Müller (1868) : 

 "stigmate sessili . . inæqualiter in lobos 3 — 4 acutos fisso"; Bentham 

 gives (1878): "a thick 2- to 4-lobed stigma"). In fruiting specimens 

 the stigma is still discernible as a small, somewhat irregular knob. 

 The fruits (Fig. 20) are oblique-ovoid or ovoid-lanceolate, with a 

 fleshy pericarp ; the colour is pale or yellowish olive-green, and the 

 dimensions are: length 20 — 27mm, breadth 

 8 — 10 mm. At maturity the fruits become 

 detached, rise to the surface of the water 

 and float owing to the lacunose aérenchyma 

 of the fleshy exocarp. This part of the peri- 

 carp splits irregularly from the base into 



two or three lobes (Fig. 22 a), so that the Fi S- 2L Posidoniaau- 



v & n straits, a, Connectives 



"stone" drops out and sinks to the bottom of the anthers, pollen 



as it is heavier than water. The irregular sacs thrown off (about 



. i i J» A nat - size )- b, Trans- 



dehiscence of the fruit is comparable ol verse section of a fruit 



that of the walnut (Juglans). The "stone" has ( abou .t ™t size )- c > 



v ° ' i-i Longitudinal section 



no real hard endocarp, only a thin, almost of a fruit ( 2 / 3 nat. size). 



membranous cover for the embryo. The latter 



protrudes at the apex splitting the membrane into two or three 



lobes and leaving the way open for the plumule (Fig. 22 d and e). 



No seed-testa is discernible in the ripe fruits; it has, probably, 



been absorbed during the development of the fruit. The embryo 



is large and highly differentiated (Fig. 22/); it consists of a thick. 



starch-containing central body (the hypocotylous axis) and a 



plumule (Fig. 21 b and c). Probably the main root does not develop 



much; it is seen as a tap at the lower end of the central body. 



The first adventitious root appears at an early stage at the base 



of the plumule, where even in unopened fruits a small protuberance 



indicates its position (see Fig. 21 c). 



This description of the fruits and my notes on their dispersal 



show that they are adapted for distribution by means of water. 



The same is the case with regard to the Mediterranean species, 



as appears from the publications of Caulinus (1. c), Germain 



3* 



