326 Tranmctions. 



of any special plant. Many plants would extend farther to 

 the north or the south, but they encounter competitors better 

 equipped for the struggle — i.e., more in harmony with the sur- 

 romidings than themselves. A plant which is slightly more 

 suited than another for a particular station must evidently be- 

 come the victor in the struggle for existence, although both out- 

 wardly may appear equally matched in every particular. The 

 distribution of Sojjhora chathamica is an interesting case in point. 

 Judging from the behaviour of the closely allied S. microfhylla 

 on the volcanic hills of Banks Peninsula, where this plant is 

 abundant, one would conclude that similar hills on Chatham 

 Island would be the habitat of *S. chathamica. On the con- 

 trary, it is quite absent in such stations, being evidently not able 

 to cope with the lowland forest plants, and it is confined to a 

 narrow strip of limestone country near the margin of the great 

 lagoon. In this place the difference of soil evidently equalises 

 the struggle, and it and the other lowland forest trees there 

 exist side by side (12; p. 271). 



Further, in considering the above question, the diverse origin 

 of the New Zealand flora must not be lost sight of. Roughly 

 speaking, there is a northern element, consisting of Malayan, 

 Australian, and Polynesian genera or species, which may be 

 called a " subtropical element " ; then there is a southern 

 element, consisting of South American and so-called antarctic 

 genera and species, to which must be added some endemic species 

 also, and this element may be called, with Schenck and Skotts- 

 berg, " subantarctic " (41, 42). The species composing these two 

 classes have come to New Zealand probably at very different 

 times and by slow degrees during great extensions of the land 

 surface. Some of the subantarctic species may be actually New 

 Zealand, if this country has originally formed a part of a palse- 

 oceanic continent. Between these alien plants, the subtropical 

 and the subantarctic, a fierce struggle must have taken place — 

 just such a conflict, indeed, as is now in progress between the 

 indigenous and introduced plants in New Zealand, these latter 

 mostly plants of temperate Europe. From the former struggle 

 have resulted our present plant formations, in some of which 

 the subtropical element is dominant, while in others the sub- 

 antarctic flourishes.* 



The present distribution of certain plants is of interest with 

 regard to this struggle. Thus, as pointed out before, north of 

 the 38th parallel is a powerful subtropical element. South of 



* This view I have already pubhshed in a series of " popular " articles 

 which appeared recently in various New Zealand daily papers, entitled 

 " New Zealand Plants and their Story." 



