290 A. A. HAMILTON. 



littoral sand containing little humus, and affording indiffer- 

 ent nourishment to the vegetation. 



The xerophytic device most favoured by the herbaceous 

 plants on the frontal dune slopes is succulence, — aqueous 

 tissue — the shrubs at the rear, and those on the rocky 

 headland, adopting various forms of leaf modification, 

 heathlike, crass or leathery, clothed more or less thickly 

 with a felted vestiture, or waxy coating, and with variously 

 arranged and protected stomata. The frontal slopes of the 

 dune receive the salt-laden spray from the ocean, and are 

 consequently halophytic, but the xerophytic character of 

 the vegetation on the inner slopes is due to the physical 

 factors with a desiccating tendency operating in this region, 

 rather than the effects of a superabundance of sodium 

 chloride in the soil. 



The principal colonisers on the strand are aliens, more or 

 less suspected introductions, cosmopolitan species, or plants 

 with an extra- Australian range, many of which have been 

 brought to our shores in ships' ballast, which has been 

 dumped on several of our beaches and spread thence along 

 the coast. Stockton Beach at Newcastle, and Geelong on 

 the shores of Oorio Bay, Port Phillip, are both well known 

 nurseries for alien weeds. In an interesting account of the 

 Mora of Ooode Island, 1 Mr. J. R. Tovey notes that a portion 

 of the island has been used as a dumping ground for ships' 

 ballast, and, as a consequence, the flora is now almost 

 entirely exotic. Mr. Tovey mentions, inter alia, that many 

 of the exotic species on the island are natives of South 

 Africa, and a similar occurrence of natives of that country 

 was noted among the dune flora of the Port Jackson district. 

 Many of these plants are provided with fruits whose seeds 

 are enclosed in suitable vessels for maritime voyaging. The 

 structure of the fruits is primarily designed for buoyancy, 



1 Vict. Nat., Vol. xxvin, p. 57 (1911). 



