ARID PORTIONS OF SOUTH AUSTRALIA. 103 



and escaped annual Echium plantagineum; but it is most abundant 

 nearer Quorn, especially along the Port Augusta road. It constitutes 

 the dominant species of fairly large and isolated areas. Various 

 grasses, however, make up the largest number of the herbaceous 

 flora by which the valley floor near the village is thickly covered. 

 How many of these are native and how many are introduced, however, 

 was not determined by me; but it seems possible that at least on the 

 lowest portions of the valleys there must always have been a grassy 

 vegetation, so that the grassland-forest formation of the regions of a 

 relatively large rainfall, as in portions of the Mount Lofty Ranges 

 near Adelaide, can be said to be represented at this place. 



One of the most striking communities on the Mount Arden road is 

 that of the mallee, an example of which lies about 2 miles north of 

 Quorn. The dominant species of the mallee scrub are Eucalyptus 

 odorata and E. oleosa. These are small trees with a shrubby growth- 

 habit and the canopy top characteristic of the mallee (plate 26c). 

 The scrub is fairly dense and the number of species comparatively 

 large. The following list, which is doubtless far from complete, com- 

 prises those most conspicuous : 



Acacia iteaphylla. Eucalyptus odorata. Loranthus pendulus. 



oswaldii. oleosa. Myoporum platycarpum. 



pycnantha. Eutaxia empetrifolia. Olearia pannosa. 



Cassia sturtii. Exocarpus aphylla. pimeleoides. 



Cassinia aculeata. spartea. Pittosporum phillyraeoides. 



Dodonaea attenuata. Hakea leucoptera. Rhagodia parabolica. 



Eremophila brownii. Indigofera australis var. minor. Triodia irritans. 



oppositifolia. Jasminum lineare. Zygophyllum billardieri. 



When examined somewhat in detail, the scrub reveals conditions 

 rather different from those before seen, as, for example, at Copley. 

 The larger number of individuals indicates better water relations than 

 at stations farther north or along the East- West Railway. In addition, 

 a study of the leaf-surface would probably show that the transpiring 

 area is considerably larger as well. In certain other regards, however, 

 a similarity exists. For instance, there is little shade in the scrub in 

 any of the dry localities seen, including Quorn. The mallee scrub at 

 Quorn is here compared with the mallee scrub in the Mount Deception 

 Range west of Copley. Should comparison be made with the hill- 

 slope community as a whole at Copley, all of these conditions and dif- 

 ferences would be greatly increased. 



Each of the three species of Acacia observed in the mallee scrub 

 has prominent phyllodia, but those of A. pycnantha, the "golden 

 wattle," are actually large, measuring about 13 cm. in length by about 

 2 cm. in width (plate 27c), and they are numerous on the small tree 

 also. This species is not present in large numbers in the scrub, al- 

 though, as will appear below, it forms a small grove on the river bot- 

 toms near the village. It occurs in the more moist portion of the state, 



