ARID PORTIONS OF SOUTH AUSTRALIA. 95 



schceberi. Among the most striking of the woody perennials to be seen 

 is Avicennia officinalis, which occurs between tides along the gulf. 

 Avicennia, the mangrove, forms fairly dense pigmy forests of narrow 

 width. At high tides the trees are entirely covered with water, and at 

 low tides they are left high and dry on the sandy beach. Radiating 

 from each tree are lines of short shoots which spring from superficial 

 roots. These shoots, usually 10 to 15 cm. in length, appear to develop 

 into the mature form under appropriate conditions, although all have 

 the appearance of being merely pneumatophores. In the zone where 

 they occur the mangroves are the sole species of flowering plants; 

 but farther from the water, although apparently not wholly above the 

 reach of the highest tides, is a belt of Salicornia sp. 



In earlier times the low hills, most of which are dunes and lie close 

 to the waters of the gulf at Port Augusta, must have had a fairly 

 dense population of trees and shrubs, if one can judge from the woody 

 plants found in occasional undisturbed places. Among other species, 

 the most striking forms are Acacia rigens and A. salicina, as before 

 noted, as well as Casuarina lepidophloia. The shrubs include Nitraria 

 schceberi, Sccevola collaris, Cassia sp., and some halophytes, especially 

 species of Kochia. 



Large areas occur where there is an excess of salts in the soil. Here 

 were found species of Atriplex, Bassia, Kochia, Nitraria, and Salicornia, 

 among others. 



Upon leaving the dunes and salt spots near the coast, there is a 

 marked change in the character of the vegetation. In the neighbor- 

 hood of Sterling, for example, numerous specimens of Eucalyptus sp. 

 are scattered about the plain, and along the wash leading away from 

 the mountains is E. rostrata. With the increase in altitude as the 

 foothills are crossed the number of individuals becomes greater and 

 the character of the vegetation indicates a larger rainfall. On either 

 side of the highway leading to Saltia, where the foothills spring fairly 

 abruptly from the plain, there is to be found a thick covering of 

 Atriplex and Kochia, and along the lower slopes, near where washes 

 break through, are small thickets of mallee, Eucalyptus oleosa (plate 

 25b). On the lower slopes of the higher hills, east of Saltia, occur 

 Casuarina lepidophloia, Cassia sturtii, Kochia pyrmidata, Senecio 

 anethifolius, and Eucalyptus odorata. Still farther east and across the 

 high valley east of Saltia are thick forests of mallee, E. odorata and 

 E. oleosa, and with the mallee were found Geigera parvifiora, Dodonosa 

 lobulata, Cassia sturtii, Hakea leucoptera, Pholidia sp., and others. 

 The vegetation along Saltia Creek, including the lowlands on either 

 side, possibly flood-plain, is characterized by trees of good size and in 

 fair abundance. The dominant species by the streamway is Eucalyptus 

 rostrata (plate 26a), and Callitris robusta is also fairly common. With 

 these species there occur a few individuals of Acacia iteaphylla. 



