6 



section, however, includes heterogeneous substances, and brings together species little 

 allied. It is doubtless capable of further elaboration, but only serves to accentuate 

 variation in the genus. Some kinos, e.g., E. maculata, are characteristic in 

 appearance, having an olive-green colour ; perhaps also that of E. corymbosa, of an 

 intense, almost vermilion colour. 



An exudation of less importance is that of Ilatma, A number of species 

 exude saccharine substances from the leaves and, a very few, from the trunk. The 

 list is being added to slowly, but in most cases the mannas are mere scientific 

 curiosities, and of little value in a scheme of classification. They include viminalis, 

 Gnnnii, punctata, pulverulenta, Stuart/ana. 



Petiole. — D. McAlpine and J. R. Remfrey, in Trans. Boy. Soc. Vict., 1890, 

 published a paper entitled, " The transverse sections of petioles of Eucalypts as aids 

 in the determination of species." 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, however, of more than ordinary value, and is well worthy of perusal. 



Leaf. — («) Suckers. De Candolle {Prodromus, vol. iii, 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 desci-ibed 

 from seedlings grown in pots. Pield 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 ai'e 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, viminalis. 



The list is, however, so incomplete that it is imjjossible at present to use them 

 as a broad basis of classification. Por diagnostic purposes, I personally use the 

 shape of the young leaf w^herever possible ; it is an atavistic character, and data are 

 accumulating by which we shall be in a better position to interpret it. 



The diilerence 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 the occurrence of these young or sucker leaves is so 

 very frequent in the bush. 



When a trunk is injured, new shoots make their appearance either from the "eyes " in the stem or 

 from reserve buds of the branches and twigs, or by bud.s produced from the roots below the ground. Tlie 

 leaves of these shoots, or suckers, as they are called, difier very much from the stems or branches which 

 have been broken, eaten, cut, or frozen off. 



