ARID PORTIONS OF SOUTH AUSTRALIA. 69 



Nitraria schoeberi, Zygophyllum crenatum, Z. fruticulosum, and Z. 

 prismatothecum* 



The vegetation of the Copley Plain at present is very sparse, in places 

 wanting, but in some places it is fairly abundant. Where absent, as 

 on the higher portions, the dead stumps of shrubs show that in former 

 times it also was covered by plant growth. But in a few small basins 

 without surface outlet, where there is an excessive accumulation of 

 salts, the edaphic conditions do not now and have not in recent times 

 permitted the presence of plants. On the lower and also well-drained 

 parts of the plain, on the other hand, species of Atriplex and of Kochia 

 especially occur in good size and fair abundance. Plate 7c shows their 

 leading characteristics. In order to learn the density of the population 

 of saltbushes, a census was taken at the base of Table Mountain, about 

 a mile south of Copley, at the upper limits of the plain where it joins 

 the slope of the hill. Here were Atriplex and Kochia, with some 

 specimens of a small and undetermined grass, a geranium, and a 

 mustard. The area observed measured 10 meters square. In the first 

 square 40 shrubs were counted, of which 36 were Atriplex. In the 

 second square, somewhat nearer the hill, 42 shrubs were found, of which 

 Zygophyllum fruticulosum was the dominant form, the balance being 

 Salicornia and Kochia. Plate 8a shows the character of the plants and 

 of the habitat. Somewhat farther (possibly 200 meters) on the plain 

 and well away from the slope, Salicornia tenuis was dominant, with 

 Zygophyllum present in fewer numbers than in the second square. At 

 this place there were relatively large areas quite bare of halophytes 

 other than Nitraria schoeberi, which was growing on sandy hillocks. 

 On the surrounding ground, where no perennials were found, there was 

 a very dense covering of very small plants. These were mainly an 

 annual species of Atriplex, which was largely in fruit. In such an 

 area, 1 square meter, 1,200 individuals were enumerated. 



One of the characteristic features of the halophytic flora of the plain 

 is the frequent occurrence of such forms on hillocks of various sizes, 

 mostly small, which have been built up around them through wind 

 action. Such hillocks were observed in connection with species of 

 Zygophyllum, Atriplex, Kochia, and Nitraria. In the first three in- 

 stances the result seems to be mainly incidental to the interference 

 with the wind flotation of the sand, but in the last case there is a nice 

 accommodation to the heaping sand on the part of the plant which 

 merits some attention. 



Nitraria schoeberi is a low shrub of rather diffuse habit. The branch- 

 lets are often spinose and rigid. The habit and habitat of the plant 



* The three species of Zygophyllum, it should be noted, are included here doubtfully. They 

 occur characteristically on slopes, but also were found at the edge of the salt plain; hence their 

 inclusion among the halophytes. It should also be said that certain species of Kochia especially 

 occur where the soil does not appear to carry an excess of salts. In general this study does not 

 nndertake to distinguish between the species ab to their toleration for salts. 



