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AN ECOLOGICAL STUDY OF THE SALTAIARSH 

 VEGETATION IN THE PORT JACKSON DISTRICT. 



By A. A. Haaiii/i-ox, Botanical Assistant, Botanic Gardens, 



Sydney. 



(Plates xvii. — xxx.) 



Introductory. 



Plant ecology embraces the environmental conditions relative to 

 plant distribution and adaptation throughout the world. Such 

 a study can only deal with broad generalisations, hence the 

 necessity for the critical survey of small areas in which detailed 

 observations of the behaviour of the vegetation may be con- 

 ducted . The results of these investigations, though primarily of 

 purely scientific interest, should provide much valuable economic 

 information. Forestry has already been termed applied ecology, 

 our native fodder plants are under consideration from an 

 ecological standpoint by local workers, and all branches of agri- 

 culture must eventually benefit by the knowledge thus acquired 

 of both plant and habitat. To the systematic botanist a know- 

 ledge of the structural modifications imposed upon plants by 

 environmental conditions is of extreme importance. 



Factors and Response. 

 The most potent factors affecting plant life in the local 

 marshes are the presence, in quantity, of sodium chloride in the 

 soil, intense insolation, imperfect drainage, tidal and stream 

 movement. The dominance of these agencies has resulted in the 

 production of a flora specially organised to resist their injurious 

 influence, plants with xerophytic structures attaining the maxi- 

 mum of success. Salicornia australis Sol., the largest local 

 herbaceous formation, has adopted the protective device of suc- 

 culence; the Grey Mangrove, Avicennia officinalis L., deflects the 

 light and minimises the effects of extreme insolation by presenting 

 a glossy leaf surface to the solar rays; the Swamp Oak, Casuarina 

 glauca Sieb., is practically leafless, and the vertically arranged, 

 highly cutinised, cylindrical stems of the reeds are well adapted 

 to withstand the deleterious factors operating in the marsh. The 





