108 PLANT HABITS AND HABITATS IN THE 



mile beyond Warren's Gorge, where there are many large specimens 

 of gum, probably Eucalyptus leucoxylon var. pauperita, there is at 

 one place a group of superficial roots which are exposed for a distance 

 of about 16 meters and probably extend much farther (plate 31s). 

 These were situated about 20 cm. beneath the surface of the ground. 



MALLEE AND THE MALLEE REGIONS. 



The mallee scrub is one of the largest and most distinctive plant 

 formations of South Australia. The term includes species of Eucalyp- 

 tus of especial habit of growth which may or may not be obligate. 

 In the mallee the stem is shortened into a large bulbous base, into 

 which the enlarged root-crown insensibly merges, and from this woody 

 mass there spring branches, usually of about equal length, which bear 

 leaves at their tips. Typical mallees thus have a rounded shoot, 

 canopy-like, and the general effect is that of large shrubs. Among 

 the mallees with consistent habit are: Eucalyptus bicolor, E. caly- 

 cogona, E. dumosa, E. goniocalyx, E. incrassata, and E. oleosa. 



Eucalyptus odorata is one of the species with tree habit which can 

 assume the mallee form under appropriate conditions. The enlarged 

 base of the mallee often is of very large size. Thus Maiden (1904: 93) 

 states that it becomes as much as 9 feet in diameter where the con- 

 ditions are favorable for its development. The base is flattened and is 

 firmly planted and held in the soil by the numerous roots, most of 

 which are superficial and extend outward for several meters. The 

 bulbous base is often so large that it will hold the shoot upright even 

 when all of the roots are removed. It constitutes a notable organ for 

 the storage of water. Maiden says that the base may be so full of 

 moisture that it would be an almost endless task to attempt burning 

 it out. When finally dry, however, the mallee "root" becomes of value 

 as a fuel and is largely used for this purpose. 



The mallees occur in regions with winter rains, although the total 

 amount of precipitation may vary considerably (Osborn, 1914). 

 Thus, in regions of the mallee the rainfall may range from about 9 

 to 19 inches. It was seen in the mountains west of Copley, in the 

 sandhill region at Ooldea, near Saltia, and at Quorn. At Ooldea the 

 mallee is growing under a 9-inch rainfall, but at the other places it is 

 more than this, and a relatively large rainfall (or at least relatively 

 good water relations) is apparently a prerequisite to the attainment 

 of the largest growth of the mallee. 



In the northern or central portions of the state there are large com- 

 munities of mallee, but its largest development is attained in the 

 southern part, especially on the bottoms of the Murray River and in 

 the region to the west of Spencer Gulf. It was seen by me west of 

 the Murray River, between Blanchtown and the highlands which 

 border the Murray Basin on the west. 



