545 



Vegetation. 



At least two very markedly different kinds of habitat 

 occur near Ooldea, namely, the Nullarbor Plain and the sand- 

 hills. These will be described separately. 



Nullarhor Plain. — The plain itself bears a very open 

 vegetation of a highly xerophytic character. The soil being of 

 ^ porous nature, and one which does not easily form a dust 

 mulch, the water supply for vegetation is scanty and very 

 uncertain in amount. This is clearly expressed in the sparse 

 plant covering. On the plain itself trees or woody plants of 

 any size appear to be absent. 



The chief plants are the "bluebush," Kockia secli folia, 

 and in rather less quantity the ''saltbush," A triplex vesi- 

 ■cariiini, which occur in communities which are often sharply 

 delimited from one another. Other species of Kochia and of 

 A triple.): also occur, but in less quantity, e.c/., K. friptera, 

 V. erioclada, K. pyramidata, etc. 



These plants, which we may term the 'character plants," 

 are small bushes. 1 ft. to 2 ft. in heiofht, which stand in most 

 parts at considerable distances from one another — often as 

 much as two. to three yards (pi. xxxii., fig. 1). In spite of 

 "this condition, how^ever, in which the plants develop quite 

 independently of their neighbours, the communities are 

 usually quite pure as regards their character species. Kochia 

 '■sedifolia is much more common than Atrijjlecr, and covers a 

 much greater area of the plain. It occupies nearly all the 

 surface w^here the fine-grained red soil occurs, while Atriplex 

 vesicarium occurs in those parts where some sand is present or 

 ihe soil is deeper and looser. The latter is especially abundant 

 near the eastern margin of the plain and along the line of 

 junction with the sandhills. So far as our observations 

 extend,. Kochia w-ould appear to be more xerophytic, t>r, at 

 any rate, able to withstand drier conditions. This agrees 

 with the observations of Tate,^^2) ^vj^^o describes the plateau 

 near Eucla as covered with Kochia^ while Atrijdex occurs in 

 •slight depressions around, but not extending into, saline 

 swamps. These Chenopodiaceous bushes, which have their 

 leaves more or less densely covered with hairs or scales, appear 

 white or silver-grey in colour, and, growing as they do in a 

 •soil that also appears pale owing to the numbers of limestone 

 fragments, give a landscape at once characteristic and peculiar. 

 The observer has a sense of uniformity and vastness which is 

 unbroken by any marked change in the surface or by any 

 sign of life, either bird or animal. 



i (12) Tate, Trans. Phil. Soc, Adel., vol. ii., p. 120, 1878. 



