ARID PORTIONS OP SOUTH AUSTRALIA. 63 



The root-habits of certain species growing along the washes or by 

 the separate basins on the flood-plain of Neales River were studied 

 as far as possible. Observations of roots exposed by the washing away 

 of the banks indicate that the general course of the roots of the trees 

 was similar. Taking Eucalyptus rostrata and Acacia cambadgei, 

 especially, it was found that a prominent portion of the root-system is 

 made up of large horizontal members which may extend for a long dis- 

 tance from the central stem (plate 7a). Thus the superficial roots of 

 Eucalyptus were seen to reach out 9 meters or more and to lie at a 

 depth not exceeding 60 cm., although the distance beneath the surface 

 of the ground was usually much less. In addition to horizontal roots, 

 vertical ones were found, but none lying at angles between. In the 

 case of several shrubs whose roots were observed, it was found that an 

 analogous condition obtained — ^that is, there was evidence of direct 

 reaction to the type of rainfall which is especially characteristic of the 

 region. In Acacia stenophylla shoots arise from the superficial roots 

 (plate 7b), with a resulting and characteristic dense thicket formation. 

 Such vegetative reproduction was seen in several species in the other 

 regions visited, especially at Quorn. 



