ARID PORTIONS OF SOUTH AUSTRALIA. 115 



few that appeared to be such and none that I was quite sure of. There 

 are many species with what may be called an intermediate condition. 

 Such would be Kochia sp., Pholidia scopana, and Eremophila free- 

 lingii at Copley, and several species of Eucalyptus of different habit 

 of growth and at different places. At Quom, however, Acacia calami- 

 folia seems to have a root-system in which the tap-root is very well 

 developed and in which the laterals do not appear to exist near the 

 surface of the ground. To surely determine the point would require 

 more observations on the habits of the species than I was able to 

 make. 



Without doubt the most usual type of root-system in the perennials 

 of South Australia is the generalized form, or that type in which the 

 roots are plastic, so that under one set of conditions they may pene- 

 trate deeply, under another they may He close to the surface of the 

 ground, or finally under a third they may both penetrate deeply as 

 well as extend widely in one and the same specimen. As will be 

 gathered from what has been remarked in the preceding paragraphs on 

 speciaUzed roots, practically all of the perennials whose roots were 

 observed have the generalized root-habit. For obvious reasons, 

 however, only the more superficially placed of the roots of such plants 

 can usually be studied, but in certain instances the development of 

 such superficial roots is very marked. For example, at Warren's 

 Gorge, near Quorn, the superficial roots of Eucalyptus leucoxylon var. 

 pauperita, which lie about 20 cm. deep, were traced 16 meters away 

 from the base of the tree. Marked development of superficial roots 

 was seen in other species of Eucalyptus, including mallees, in several 

 locahties; no very deeply placed roots of species of the genus were 

 actually observed. By a wash near Quorn a penetration of 2 meters 

 was noted and the root gave every appearance of sinking deeper than 

 this. Reports, however, were not wanting to the effect that roots of 

 Eucalyptus might attain to very considerable depths and in fact were 

 not infrequently met in digging operations. I was unable to verify 

 such reports, but from what I saw of the roots of Eucalyptus I would 

 suppose deep root penetration to be possible under appropriate con- 

 ditions. 



An interesting feature of species having generalized roots is the 

 frequency with which they reproduce vegetatively. This occurs 

 through the springing of shoots from the horizontally placed roots. 

 Although the vegetative reproduction was not studied especially, it 

 was noted at Quorn mCasuarina sp., Hakea leucoptera, and Templetonia 

 egena, and observed at other places and in other species. 



Especial study of the roots of the perennials of the state will prob- 

 ably show many interesting forms of specialization and adjustments 

 to the physical environment which may be of moment in the survival 

 of the species. It does not seem improbable, for example, that roots 



