463 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
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