68 PLANT HABITS AND HABITATS IN THE 



which about 20 per cent occurs in amounts too small to benefit plants 

 directly. 



The following glimpses of the vegetation, its leading character, and 

 occurrence, taken at a few well-marked localities close to Copley, 

 should supply in a broad way sufficient data to reconstruct its general 

 features. 



For convenience the description of the vegetation at Copley will be 

 grouped around the following physiographic units (habitats), which 

 will be made the centers of "communities," but they are probably not 

 of equal value, as will be at once apparent: 



(1) "Alkali" plains, or lowlands, including slopes and benches where 

 halophytic vegetation points to an excess of salts in the soil. 



(2) Low hills and the slopes of higher hills, or low mountains, as 

 of the Mount Deception Ranges west of Copley and the lower portions 

 of the Flinders Ranges to the east. This includes the subaerial delta 

 fans(?) on either side of the Copley Plain. The leading features of the 

 hill habitat can be said to be (a) possible variations in aspect; (fe) 

 a relatively good water relation through altitude and relation to higher 

 hills or mountains; and (c) presence of rock outcrops with correspond- 

 ing paucity of soil whose nature is determined by that of the rocks. 



(3) The Mount Deception Range immediately west of Copley. 



(4) The washes or streams in the hills and lowlands. 



' Vegetation of the "Alkali" Plains. 



The most important component of the vegetation of the lowlands, 

 particularly of the Copley Plain, consists of halophytes in bewildering 

 variety. These in large part are very similar in size and in general 

 appearance and it needs fairly close study to distinguish many of them. 

 They are 50 cm. more or less in height and usually of a grayish-green 

 color ;* but some are small annuals and some occur in communities having 

 a common ancestry, which are of considerable extent. As a whole, the 

 halophytic flora of the far north is'of great economic importance, inas- 

 much as it constitutes practically all of the forage of this vast region, 

 being thus the basis of the pastoral industry.* 



The following species of halophytes were observed on the Copley 

 Plain or on slopes contiguous thereto: Atriplex spongiosum, A. vesi- 

 carium, A. quinii, Kochia pyrmidata, K. planifolia, K. cannoni, 

 K. villosa, K. decaptera, K. eriantha, K. sedifolia, Enchylcena tomentosa, 

 Bassia laniicuspis, B. paradoxa, and Salicornia tenuis. In addition, 

 "salt-loving" species of other families were found, among which were 



* In 1912 the Central, Lower North, and Upper North of South Australia supported the follow- 

 ing number of live stock: cattle, 199,727; horses, 197,139; sheep, 2,674,856 (Handbook of South 

 Australia, 1914, p. 143) ; there are also several thousand camels. Besides the domestic animals 

 which derive their entire subsistence from the native flora, there should be mentioned the native 

 and introduced wild animals which also subsist wholly on it. Of these, the most destructive are 

 the rabbits. They occur during favorable periods in countless numbers and work great harm to a 

 very wide class of vegetation, including that useful to sheep, cattle, horses, and camels. 



