396 



For comparison with these we repeat as sample No. 5 the analysis of 

 soil from the A. stipitatum community at Port Wakefield. This, as was 

 explained in our previous paper, is a degenerate saltbush community owing to 

 human interference, but the relics of the vegetation suggest a community of 

 the type described above. The analysis shows a soil of similar water-retaining 

 capacity, but with more soluble salts, though appreciably less sodium chloride. 



Mallee saltbush community is more prominent in the south of the area 

 under discussion than in the north. From the rainfall diagram (text fig. 2) it is 

 seen that the annual precipitation in the south (e.g., Florieton) is greater and 

 also shows a more pronounced winter maximum than the northern stations. 



Kochia planifolia community. 



Kochia planifolia — a bluebush — forms a very uniform community over 

 the country around Curnamona. The terrain here is an even plain with no 

 marked physical features. The dominant plant forms rounded shrubs, '5-1 meter 

 in diameter. The bushes branch freely and bear numerous sub-cylindrical leaves, 

 slightly flattened above and somewhat constricted at the base. The leaves are 

 1-2 cms. in length, covered by a dense tomentum of hairs. The bushes are 

 scattered with 3 or 4 feet of bare ground between neighbouring plants (pL 

 XXXV., fig. 3). 



Scattered, tall shrubs occur over the Kochia planifolia community. These 

 are Cassia Sturtii, Eremophila Sturtii (turpentine bush), and E. glabra (tar 

 bush). The individual bushes are about 2 m. in height and often occur in 

 small thickets. Trees, chiefly mulga (Acacia aneura), occur rarely, being 

 Mmited to local groves where the soil is more sandy. 



Kochia planifolia usually forms a remarkably pure community. In places,, 

 .lowever, there is associated with it K. Georgii, K. pyramidata, or even 

 Atriplex vesicariiim. 



Soil from the K. planifolia community is analysed as sample 6. In appear- 

 ance it is a reddish loam, distinctly more compact than that on which most of 

 the Atriplex vesicariuni communities occur. Analysis shows that the soil has 

 a lower water-retaining capacity at saturation and is poorer in soluble salts 

 (08 per cent., of which only 02 per cent, is sodium chloride) than the soils 

 previously described. We are of opinion that K. planifolia forms a community 

 of a more xerophytic type than Atriplex vesicarium. 



Kochia sedifolia community. 



Kochia sedifolia, the most widespread bluebush in South Australia, occurs 

 as a pure community in parts of the area, being associated with soils on travertine 

 limestone. In the Murray Basin this community is often extensively developed, 

 though the local abundance of the plant may be in some degree secondary, owing 

 to selective grazing, K. sedifolia being less acceptable to stock than Atriplex 

 spp. At Dilkera, K. sedifolia grows with Atriplex vesicarium and A. stipitatum 

 under an overgrowth of mallee and Myoporum platycarpum. Near Morgan, on 

 the Murray, there are extensive areas of K. sedifolia and M. platycarpum form- 

 ing an obvious degenerate community owing to grazing. 



Adamson and Osborn have described an extensive K. sedifolia community 

 on the Nullabor Plain at Ooldea. They are of opinion that it is of a more 

 xerophytic type than the Atriplex vesicarium community. With this deduction 

 our results obtained in the present investigation are in agreement. 



Arthrocnemum halocnemoides, var. pergranulatum, community. 



This community is developed on gypsum salt swamps. In general appear- 

 ance the variety is similar to the typical form of the species found on the saline 



