TOPOGRAPHICAL, ECOLOGICAL, AND TAXONOMIC NOTES. 347 



and branches of the plants are interlocked for mutual pro- 

 tection against dislodgment by flood waters. The bulk of 

 the ligneous vegetation has been removed from the com- 

 paratively flat stretch of dune at the rear of the strand* 

 two Banksias, B. cemula R. Br., and B. serrata L., repre- 

 senting the remnant of the arboreal growth. 



These two species may be easily confused when growing 

 on the exposed headland, where they both approach the 

 shoreline, in places, to within a few feet of the escarpment 

 and are reduced by exposure to low spreading shrubs. When 

 growing under normal conditions the habit of these plants 

 is a sufficient guide to their identity, B. cemula rarely 

 exceeding the dimensions of a large shrub, its stem furnished 

 with branches almost to the base, B. serrata attaining the 

 rank of a medium sized tree, with a clear trunk several 

 feet from the ground. Photographs of examples of both 

 species domiciled at no great distance apart on the dune 

 flat at Long Bay, showing their distinctive habit have been 

 incorporated by Mr. Maiden in his "Forest Flora of New 

 South Wales," iv, p. 30, 1909. B. serrata usually maintains 

 a large colony, covering in some localities, several acres of 

 ground, its confrere, less exclusive, usually assembling in 

 small groups or growing as individual specimens among the 

 shrubbery. 



On the cleared area several herbaceous species with 

 subterraneous root systems of vegetative reproduction, too 

 deep to be destroyed by fires, which are of frequent occur- 

 rence, have seized the opportunity for colonisation, and 

 taken possession of the vacant space, either as segregated 

 assemblies or in association. Of these the cosmopolitan 

 Bracken-fern, Pteridium aquilinum (L) Kuhn., is the most 

 aggressive, extending over the greater part of the dune flat 

 and invading the Banksian arboretum, its greedy rhizomes 

 absorbing the small quantity of nutriment available in the 



