252 



a plant of remarkably varied habitat and possessing also a capacity for adven- 

 titious rooting. (^^^ 



All the other islands seen represented older stages than that just described. 

 By successive deposition of more shells and debris the level of the islands had 

 become raised well above the general level of the plain. The banks so formed 

 were colonized by a mixed community of various shrubs, low trees, and annuals. 

 The following is a composite list made from three such islands : — 



Stipa terctifolia Silene gallica 



Avena fatna Tillaea verticillaris 



Bromus sp. Acacia ligulata 



Dianella revoluta Nitraria Schoeberi 



Fusanus acuminatus Frankenia pauciflora 



Exocarpus aphylla Alyxia buxifolia 



Rhagodia baccifera Myoporum insulare 



Atriplex paludosum Olearia axillaris 



Threlkeldia diffusa Vittadinia anstralis 



Tetragonia implexicoma Senecio lautus 



Mcsembryanthemimi aequilaterale 



The soil analysis shows that the soil has a very low water retaining capacity ; 

 the soil was air dry when collected, with only 16 per cent, of moisture. That 

 the soil is chiefly made up of shell grit is seen by the lime content of 907 per 

 cent. Soluble salts in the soil were only 11 per cent., of which only 006 per cent, 

 was sodium chloride. 



Mosses were a prominent feature of the ground flora, and saxicolous lichens 

 were present in quantity on the superficial layer of shell. The ecology of these 

 islands and the relation of the florulas to that of the coastal dunes in the vicinity 

 would be of interest, but it is not proposed to consider them further here. Atten- 

 tion may be drawn to the occurrence of Atriplex paludosum on the "islands," 

 for they provide an obviously non-halophytic habitat. 



Atriplex paludosum consocies. 



A dwarf shrubland of Atriplex paludosum occupies the upper limits of the 

 coastal plain. The grey colour of the dominant plant at once characterises the 

 area, distinguishing it sharply from the Arthrocnemum halocnemoides shrubland 

 on the seaward side. The ecotone line is sharp, a distance of three or four yards 

 usually being sufficient to pass from the samphire community of the type described 

 above to pure saltbush. The soil analyses of the transition regian are given as 

 No. 7 from A. halocnemoides zone and No. 8 near the junction, but definitely 

 in the A. paludosum zone. The percentage of moisture in the soil as collected 

 and of sodium chloride in No. 8 is only 50 per cent, of that found in No. 7., 

 It will be seen, also, that the moisture content of the air dry soil indicates a 

 lower water retaining capacity for the soil supporting the saltbush community. 

 The Atriplex paludosum consocies is thus developed on a soil that is only 

 moderately salt but with a low water retaining capacity ; it is, in fact, a plant 

 community developed on a xerophytic habitat rather than a halophytic one. 



The following plants also occurred : — 



Poa bulbosa Mesembryanthemum australe 



Thysanotus Patersonii Tillaea verticillaris 



Atriplex semibaccatum Frankenia pauciflora 



Bassia uniflora Angianthus strict us 

 B. bi flora 



(13) Cannon, W. A., loc. cit., p. 70. 



