BY MAKJORIE I. COLLINS. 383 



The ilevelopment of saltmarsli commences almost simultaneously with that 

 of mangrove. Here Salicomia australis Soland. is the jiioneer plant and often 

 establishes itself to the exclusion of other species. In parts of the George's 

 River and Botany Bay large areas are occupied by pure Salieornietum (Hedley, 

 1915, p. 46). 



It is more generally found, however, tliat Suaeda australis follows Salicomia 

 closely and becomes a co-dominant witli the latter in the initial stages of Salt- 

 mai-sh.. 



In order to understand the conditions which exist on the majority of tidal 

 flats near Sydney, it is necessary to study the vegetation over a continuous 

 period of time. It is only thus that developmental phases may be recognised 

 and the true limits of the association established. Tlie writer recognises two 

 plant associations in salt marsh formation near Sydney : — 



(i.) An outer mixed saltmarsli association corresponding to tlie "mixed 

 salting" of British investigators (Carey and Oliver, 1918; Tansley, 1911). Since 

 Salicomia australis is the dominant species here, the writer will refer to this as- 

 sociation as Salieornietum. 



(ii.) An inner almost pure association of Juiicus maritimus which usually 

 marks the boundary between the marsh and land flora — the Juucetum. 



i. Salicorni.eium. 



On young Salicomia association it is possible to recognise at lea.st three 

 developmental phases or associes in Clement's sense (1916, p. 136). These 

 appear to be associated with slight differences in level and are present as zoned 

 bands which show a certain amount of overlapping. The lowest of these, which 

 abuts on the mangi-ove formation is the (a) Salicorma-Siiaeda associes, charac- 

 terised by Salicornia amtralis Soland. and Suaeda australis R. Br. These low 

 succulent shrubs are inundated by all tides and together with the pneumatophores 

 of Avicennia officinalis play an important part in the building up of the marsh 

 by acting a.s retainers of silt. (h). At a slightly higher level is an associes in 

 which Salicomia and Spergularia rubra are developed equally with a number of 

 low spreading perennial halophytes. The plants of this associes arranged in 

 order of dominance are:— (1.) Salicornia australis Soland. (ii.) Spergularia 

 rubra Camb. (iii.) Suaeda australis R. Br. (iv.) Samolm repens R. Br. (v.) 

 yiesembryanthenmm tegeiis F. v. M. (vi.) Tetragonia ,expansa Murr. (vii.) 

 Atriple.T patula L. (Introduced) (viii.) Wilsonia Backhousii Hook. 



(c). Sporobolus-Cynodon associes which occupies a marginal jiosition 

 within the association and is of sward-like physiognomy (PI. xxviii.. Photo 7). The 

 chief constituents are Sporobolus virginicus Humb. and Kunth., Cynodon dactylon 

 Rich, and Zoysia pungens Willd., but as there is no strong line of demarcation 

 between these latter associes, particularly where the slope is gradual, there is 

 often a profuse mingling of perennial halophytes with the above-mentioned 

 grasses. That these are developmental phases of the mature Salicomia associa- 

 tion is shown clearly in old saltmarshes, where the level has been raised by silt 

 accretion and a fairly uniform surface prevails. Here a mixed association of 

 annual and perennial lialophytes is found occupying the whole area between the 

 inner Juncetum and the outer mangi-ove formation. In this mixed meadow-like 

 association, Salicornia and Siuieda are predominant on the outer margin, since 

 here seedlings have a better chance of establishing themselves. Where bare 

 patches are found in this association owing to destruction of underlying vege- 

 tation by decaying detritus, algal mats, and the like (Harshberger, 1916) the 

 pioneer colonist Salicornia is not slow in making its appearance. Thus, in 



