Comparative Constancy of Specific Characters 

 of Eucalyptus Species. 



THE reputed or supposed great variation of individual Eucalyptus species has 

 arisen probably by the attempts of botanists to found species on morphological 

 characters alone ; and Bentham, when working on this system, experienced great 

 difficulty in finding any constant feature upon which even to establish groups, 

 and had to discard such differences as opposite or alternate leaves, comparative 

 length of the operculum, length of calyx tube, &c. He finally selected the shape 

 of the anthers as a means of classification, but even this has since been found 

 to be defective and is open to objections. Bentham evidently felt that even 

 this was not such a natural classification as he would wish, because in his remarks, 

 (B. Fl., iii, p. 186), he expresses a hope that a " truly natural arrangement 

 may be founded on a knowledge of the ' Gum ' trees in a living state, upon the 

 proposed cortical or on any other system u'hich experience mav suggest." However, 

 we are quite in accord with him when he states, concerning his classification, 

 that " the groups pass very gradually into each other through intermediate 

 forms," and our results confirm this gradation of groups; but it is the individual 

 species that shows a comparative constancy of specific characters throughout 

 its known geographical distribution. Not only is this the case with the 

 botanical characters, but also in their chemical constituents, a conclusion fully 

 confirmed by the mass of evidence we are now able to submit in connection with 

 the species here enumerated, and as the result of a research extending over a 

 period of thirty years. 



The most serious objections to Bentham's antheral system are : 



1. That of placing in the same group, and in juxtaposition, species which 



to those familiar with the trees in the field, are perfectly distinct from 

 each other ; and 



2. That of separating under various sections trees which by bark, wood, 



habit, general characters, chemical properties of their oils, kinos, dyes, 

 &c., ought to stand near to each other. 



For instance, in the former case, with the smooth-barked " Mountain 

 Gum " (E. goniocalyx) , the " Bundy Box " (E. elceophora], was confounded or 

 associated. The " Apple " of Victoria, with its red timber and stringy bark, 

 was placed with the " Apple "or ' Woollybutt " of New South Wales (E. 

 Bridgesiana), a tree with a pale-coloured timber, and a " Box " bark; numerous 

 other examples could also be given, and similar associations will no doubt occur 

 to any student of the Eucalypts. 



The second case could be illustrated by the " Ironbark " trees, which 

 might be grouped together, but yet stand apart ; whilst with them were 

 included the " Scribbly Gum" (E. hcemastoma), "Tallow-wood" (E.'microcorys), 

 and others trees which have quite distinctive characters and should be 

 separated. 



Probably it has been the effort to utilise this and similar systems that 

 has led to the acceptance of the idea of great variability of Eucalyptus species, 

 but from the results of this extensive study we consider that only in exceptional 

 cases do such nuances exist, even under a natural classification. 



