ARID PORTIONS OF SOUTH AUSTRALIA. 75 



the sole species, as at the habitat mentioned, they form one of the 

 mcst striking communities of the whole region (plate 10c). 



A mono-specific community of quite a different character was ob- 

 served on the upper slopes of hills leading up to the eastern summits of 

 the Mount Deception Range, about 4 miles to the west of Copley. 

 When viewed from the plain, there appeared at this place a bright- 

 green area, as^of a grassy field. When it was reached, however, by the 

 way of the lower hills, it was found to consist wholly of Zygophyllum 

 crenatum, a low, spreading annual. There was no other species of 

 any sort over the rather large area, possibly of several acres. 



Among other species, which occur in large numbers to the exclusion 

 of others, is Cassia sturtii. This is a somewhat diffuse shrub about 

 1.5 meters high. It appears to have been much more abundant in 

 former times in the vicinity of Copley, if one can judge from the 

 large areas which now are covered with specimens no longer living, as 

 on certain slopes of the Mount Deception Range. At present, how- 

 ever, it is conunon enough. Frequently, as among the rounded hills 

 along the Mount Series road about 5 miles east of the village, it forms 

 fairly large communities (plate 10a). It seems to be restricted to hills 

 and slopes. 



Another example of a mono-specific community is that of Kochia 

 sedifolia, which, unlike so many of the family, appears not to tolerate 

 a large amount of salts in the soil, so that possibly it may not be con- 

 sidered a strict halophyte. It occurs on slopes which are often, but 

 not always, somewhat above the plain. The situation of the habitat 

 to be described is along the Yudnamutana road, about 2 miles north- 

 east of Copley, where an intermittent stream, making its way across a 

 slope from hills farther east, has cut a fairly deep gorge. To the south 

 of the edge of the latter the slope dips gently to the Copley Plain. 

 The population is fairly sparse, as the habitat shows, (plate 7c). The 

 individuals are about 50 cm. high and of a very close, compact growth- 

 habit. The species occurs to the exclusion of others over an area 

 many acres in extent. 



Zygophyllum fruticulosum is another species which may occur solely 

 in a habitat. This small shrub, of a lax growth-habit, grows on the 

 lower slopes of the Mount of Light as well as on nearby slopes to the 

 exclusion of other species of perennials. The habit and distribution 

 of the species, as well as the character of the habitat, are fairly well 

 shown in plate lie. 



An additional species, which occurs with little or possibly no aa 

 mixture of other species in certain areas, is Eucalyptus oleosa. This 

 is one of the "mallees." Although the mallee does not form a 

 conspicuous member of the plant community at Copley, it is to be 

 found scattered along the washes, and at a place about 4 miles west of 

 the village and in the Mount Deception Range a mallee thicket has 



