36 R. H. CAMBAGE. 



distinct effects amidst different surroundings. For this 

 reason therefore extreme caution should be exercised in 

 any attempt to interpret the significance of any particular 

 leaf modification. 



The mature or adult Eucalyptus leaves which are often 

 falcate, are disposed vertically in the great majority of 

 cases, so as to present the least possible surface to the 

 sun, and thus minimise transpiration or the vaporising of 

 water which is in the leaf. Eucalypts have also in many 

 cases reduced their leaf surface, while in a few instances 

 they appear to have increased it, as may be seen by a study 

 of juvenile and mature foliage on the same tree, the 

 juvenile foliage being regarded as more nearly representing 

 the ancestral form. 



Large and small leaves. — In considering the large and 

 small forms of mature leaves, the former may be regarded 

 as including those which are either long or broad, and the 

 latter, those which are either short or narrow. The largest 

 are commonest in the Mountain Region, the second largest 

 in the Ooastal Area, the third on the Western Slopes, and 

 the smallest in the Interior. Having in view the question 

 of adaptability to environment, this distribution is exactly 

 what might be expected, the cool or moist divisions having 

 the largest leaves and the driest area the smallest. At 

 the same time there are exceptions to this general rule, 

 for while the sheltered portions of the Mountain Region 

 produce such trees as E. globulus and E. goniocalyx with 

 leaves often upwards of a foot long, the more exposed 

 portions are the home of such trees as E. Moorei and E. 

 parvifolia with narrow leaves from two to three inches 

 long. 



Thick and thin leaves. — The thickening of the epidermis 

 for the purpose of sheltering the stomata, is one of the 

 expedients resorted to by the Eucalypts to resist evapor- 



