IS EUCALYPTUS VARIABLE % 323 



The method of classification on the comparatively few 

 experiments made is ingenious but of little practical value 

 to us for diagnosis, thousands of sections being required in 

 order to obtain data for generalisation. The paper is how- 

 ever, of more than ordinary value and is well worthy of 

 perusual. 



Leaf — (a) Suckers — De Oandolle (Proclromus Vol. ill., 

 1828) classified Eucalypts according to the opposite or 

 alternate character of the leaves, a character of special 

 importance at that time since species were often described 

 from seedlings grown in pots. Field observations have, 

 however, shown that all species have opposite leaves in at 

 least an early stage. In seedlings this is best observed, 

 but in many cases suckers show the character quite as 

 well. In a few species e.g., gamophylla, this opposite- 

 leaved character persists through life. In many cases the 

 young leaves are broad and become alternate and narrower, 

 with a lanceolate or falcate shape as maturity is reached. 

 Often these young leaves are glaucous, becoming glabrous 

 as growth proceeds. But there is a group in which the 

 seedling and sucker leaves are narrow. Such species 

 include amygdalina, pilularis, vlminalls. 



The list is however so incomplete that it is impossible 

 at present to use it as a broad basis of classification. For 

 diagnostic purposes I personally use the shape of the young 

 leaf wherever possible; it is an atavistic character and 

 data are accumulating by which we shall be in a better 

 position to interpret it. 



The difference between suckers and mature leaves has 

 been studied in Europe for many years, although in 

 Eucalyptus the systematic comparison of such forms is of 

 comparatively recent date. It is of practical importance 

 to the Australian forester, for the reason that tiie occur- 



