378 MAKGKOVE AND SALTMARSU VEXJETATION NEAR SYDNEY, N.S.W., 



formation of mud flats and their c-olonisation by plant and animal life, would 

 necessarily be postponed until a condition of equilibrium had been attained. 

 Once the bank of muddy silt is raised above low tide level, seedlings of Avicetniia 

 officinalis Linn. (Australian Grey Mangrove) establish themselves, and aid in 

 the building up of a mud flat. The mud is generally black and of a coarse, 

 sandy nature, punctured at frequent intei-\-als by crab-holes (.vpp Hedley, 1915. 

 p. 46) and becoming foetid from the decay of various Algae, shellfish and drift 

 material. These play an important part in providing humus and in aiding the 

 building up of the flats. 



The Vegetatio.v op the Tidal Flats. 



The tidal lands which come within the scope of the present paper aie to 

 be found chiefly in the upper reaches of the Iron Cove, Parramatta River, Lane 

 Cove River, and Middle Harbour — all arms of Port Jackson; along the banks 

 of Cook's and George's Rivers flowing into Botany Bay. and in tlic sheltered 

 arms of Port Hacking. The area ranges from 33° SO" to 34° 5', S. Lat. and 

 extends from Port Jackson south of Sydney for a distance of about sixteen 

 miles (Text-fig. 1). 



The area in Fort Hacking to which the writer has given special attention 

 is that of Cabbage Tree Creek, where an interesting series of changes is taking 

 place, owing to the raising of the level of the saltmarsh by wind-blown sand. 



Previous Investigalious. 



Extra-tropical mangrove and saltmarsh vegetation in Australia has Ijeeii 

 dealt with by but few writers. In his description of tidal woodland, Sehimper 

 (1903, p. 409) records the occurrence of the mangroves Avicennia officinalis 

 Linn. (Verbenaceae) and Aegiceras majm Gaertn. (Mi/rsitiaceae) on the cua.st 

 of New South Wales. This record is briefly descriptive and deals with the 

 nature of the viviparous seedlings in the two genera (p. 400). 



Hedley (1915, pp. 44-46) records the same species for Port Jackson and 

 gives Wilson's Promontory in Victoria as the most southerly station in Australia 

 for Avicennia officinalis. 



In a preliminary account of the coastal vegetation near Adelaide. Osborn 

 (1914, pp. 584-586) records Avicetniia officinalis as the only mangi-ove present. 

 This writer also refers to the presence of Suaeda maritima^ mingling with the 

 mangrove on its shoreward side. Salicornia swamps (with Salicornia australts 

 Soland. and S. arhusciila R. Br.^) which are only subjected to occasional tidal 

 inundation, are found on the shoreward side of the mangrove. Zonation is 

 reciirded in these swamps, the zones being as follows: "(1) Salicornia; (2) 

 Salicornia and Snmolus repcns; (3) Sanwlm repens and Sporolioliis virginicKS; 

 (4) Sporohohis, Spergularia, etc." 



Western Australian extra-tropical mangrove has been dealt witli by Dr. C 

 H. Ostenfeld (1918, pp. 1-12). This writer recognises three shore line forma- 

 tions on the coa.st of Western Australia, south of the Tropic. 



1. Mangrove Formation. 



2. Sandy Sea Shore Formation. 



3. Salt Pan Formation. 



'See reference to Paulsen Vielow. 



tRecent investigiitions by Black (1919) into South Australian Salicornieae point to 

 the plant hitherto known as SaHcornia arfirisrnfaheiag in reaWtyArtlirociieJiiuvi arbusciila. 



