472 ECOLOGICAL 8TUDY OF SALTMARSH VEGETATION. 



tidal waters at Clyde, a belt of Mangroves is bordered by a sward 

 of Salicomia, the line of demarcation between the formations 

 showing a cleavage as sharply defined as the verge of an arti- 

 ficial lawn bordering a footpath. The invasion of the Mangrove 

 forest is initiated on its landward boundary, where the uplift 

 of the marsh by the accumulated debris has stabilised the muddy 

 surface and created a situation favourable to the Salicomia. 

 Isolated plants of the latter, and its occasional rival but more 

 frequent ally, Suaeda maritima, evade the defending pneumato- 

 phores and gain a precarious foothold among the dwarfed 

 shrubby Mangroves on the fringe of the forest. Their presence 

 assists the factors already operating to render the position un- 

 tenable to the Mangroves and, as they retreat, the Salicomia 

 which in this station outstrips its shorter-lived associate, occu- 

 pies the vacated area. At the head of Iron Cove, the formation 

 of a road through the marsh has made a clearing in the Man- 

 grove forest, and the first to enter the breach were the Salicomia 

 and Suaeda. A similar occurrence was noted at Homebush Bay, 

 a third herb, Atriplex patula, also obtaining a footing in the 

 broken Mangrove formation. 



Near the mouth of Cook's Kiver a group of Mangroves has 

 been felled and the area is overrun by Salicomia. Several young 

 Mangroves have sprung up, but are unable to attain an arboreal 

 development, the close carpet of Salicomia, favoured by the 

 collection of soil and detritus, placing them at a disadvantage. 

 On an open reach of the Parramatta Kiver at Meadowbank, the 

 Salicomia exhibits" antipathy for a sandy habitat, its formation 

 breaking up while in transit from the marsh mud to the sandy 

 shore upon which its further progress is arrested. 



On the tide-flooded plain the Salicomia is an almost pure 

 culture with a remarkably even compact carpet rarely exceeding 

 a few inches in height, the stems developing the short internodal 

 growth attributed by most writers to the effects of intense insola- 

 tion. Where it ascends the drainage channels, it is frequently 

 built up, in shoal water, into hummocky patches, the stems at- 

 taining a length of 1J — 2 feet. On the marsh plain, individual 

 plants are usually arranged in spreading radial tufts, the closely- 

 knitted, shortly-rhizomatic, procumbent stems buried under the 

 silt to a depth equal to the emerged portion. As the stem 

 disappears beneath the soil it loses its succulence and develops 

 a tough wiry rhizome, which produces adventitious roots plenti- 



