TOPOGRAPHICAL, ECOLOGICAL, AND TAXONOMIC NOTES. 325 



Rottb., and sprawls among the lax stems of the Sheep's 

 Sorrel, Rumex acetosella L., the latter indicative of a sour 

 soil; and the Bushy Star- wort, Aster subulatus Mich., of 

 the North American salt-marshes finds in this environment 

 a satisfactory substitute for its natural habitat. As a 

 result of the bad drainage and lack of aeration, the tufts of 

 Seirpus nodosus located in the muddy area have become 

 debilitated, and the weakened stems unable to maintain 

 their normal erect habit are relaxed and prostrate. 



Two Rutaceous undershrubs, Zieria Icevigata Sm., and 

 Eriostemon Crowei F.v.M., are well represented on the 

 sandstone hillside, to which they are edaphically restricted. 

 Both species extend from Victoria to Queensland, and 

 ascend the eastern slopes of the dividing range to the table- 

 land. The Blue Mountain form of Z. Icevigata was 

 described as a distinct species under Z. revoluta by Allan 

 Cunningham, in "Field's New South Wales," p. 330, but 

 was later reduced by Bentham, (Fl. Austr. i, 304) to a 

 synonym of the former species. The Dwarf Apple, 

 Angophora cordifolia Oav., a local species found on the 

 coastal sandstone from Woy Woy to National Park, forms 

 small exclusive colonies. 



Two forms of the Geebung, Persoonia lanceolata Andr., 

 differing chiefly in size of leaf, occur on the hillside, both 

 maintaining their distinct leafage on the landward sand- 

 hills. Ricinocarpus pinifolius Desf., Trachymene linearis 

 Spreng., Acacia juniperina Willd., and Styphelia ericoides 

 Sm., have all narrowed their leaves with a transpiration 

 reducing objective. Epcicris longifiora Oav., is very 

 susceptible to the influence of shade, moisture and drainage, 

 plants growing within a few yards of each other quickly 

 responding by enlarging or reducing their foliage as these 

 factors are favourable cr the reverse. Styphelia tubiflora 

 Sm., a twiggy undershrub, occurs in isolated patches on 



