TOPOGRAPHICAL, ECOLOGICAL, AND TAXONOMIC NOTES. 309 



rhizomes, which root below each tuft, simulating under- 

 ground, the action of the Spinifex on the surface. Behind 

 the Oarex a colony of Scirpus nodosus is in possession of 

 the dune slope, its scattered clumps penetrating the 

 fringe of a forest of Banksia integrifolia. 



The Banksia continues the sequence as a pure culture, 

 inland to the Pittwater road, where its association is 

 intruded by a few trees of the " Blood- wood," Eucalyptus 

 corymbosa Sm. The "Swamp Oak," Casuarina glauca 

 Sieb., has here demonstrated its adaptability, by ascending 

 the dry sandy hill to a considerable distance from its normal 

 habitat on the margin of the lagoon. 



South of the entrance to Deewhy lagoon, an association 

 of Aplum prostration Labill., the "Australian Celery," is 

 established among the Spinifex. When growing in close 

 proximity to the strand, this diffuse herb incurves the leaves 

 on its exposed margin, presenting a rounded surface to the 

 wind and spray. On the dune the plants are solitary, but 

 in moist situations in the soil pockets and crevices on the 

 rocky ocean escarpment, they frequently form confluent 

 mats in association with Lobelia anceps Thunb., and 

 Samolus repens Pers. 



The dune vegetation from this point to beyond the centre 

 of the beach is herbaceous, one plant (dwarfed) of Lepto- 

 spermum Icevigatum, and a few bushes of Styphelia Richei 

 Labill., on the frontal slopes, were the only shrubby growths 

 noted. The latter, a halophilous species which does not 

 travel far inland, displays a partiality for the dune, rarely 

 extending to the rocky escarpment or hillside. Its suscep- 

 tibility to exposure is invariably expressed by dwarfing 

 (nanism), a considerable degree of shelter being necessary 

 for the attainment of its maximum stature. 



The rearward dune slope trending towards the waters of 

 the lagoon is carpeted at its base by a lawn of Zoysia 



