Thomson. — Plant- acclimatisation in New Zealand. 319 



birds, or insects, though there is no inherent improbability 

 in this mode of introduction. Many of us can recall the sultry 

 day a few years ago when the sky was darkened and the sun 

 became lurid from the dense smoke of Australian bush-fires, 

 and it is quite clear that light seeds and spores might very 

 easily be carried along at considerable elevations by a similar 

 westerly wind. Many of our native species of flowering- 

 plants are either identical with or closely allied to Australian 

 forms, and this is particularly the case with such plants as 

 the pappus-bearing composites — e.g., Celmisia longifolia, Cras- 

 pedia fimbriata and C. alpina — several species of Erechtiies, 

 &c, and the various species of Epilobium (E. confertifolium, 

 E. glabellum, E. junceum, &c), which have a tuft of hairs on 

 the seeds. 



Again, on the west coast of the North Island, and particu- 

 larly on the peninsula north of Auckland, Australian birds 

 have been met with which had managed to survive the long 

 flight across the Tasman Sea. Such birds are probably weak 

 from exhaustion on reaching the shore, and are killed by 

 gulls or other enemies, those which survive dyiug in the 

 course of time without reproducing their kind. Such birds 

 may bring seeds in their crops or stomachs (though this is 

 not very likely after such a long flight), or they may have 

 seeds attached to their feet or their feathers. Both the 

 cuckoos, too, come to us from across the seas — one from 

 Australia and the other from the South Sea Islands ; while 

 migratory birds like the sandpipers, &c, travel vast distances 

 from shore to shore. Yet, with all these possible modes of 

 conveyance, we cannot point to a single instance of plant- 

 naturalisation due to these agencies. 



A large proportion of the plants which have succeeded in 

 establishing themselves in this country belong to what Sir 

 Joseph Hooker has called the " Scandinavian flora," the ag- 

 gressive and colonising power of which has been dwelt upon 

 by him, by Charles Darwin, and by A. E. Wallace. Darwin's 

 explanation, it may be remembered, is that this power of 

 colonising is due to the development of these plants in the 

 most extensive land-area of the globe, where competition has 

 been most severe and long continued. A discussion on this 

 subject will be found iD the chapters dealing with the flora 

 of New Zealand in Wallace's " Island Life," and much ad- 

 ditional information is also given in his " Darwinism." 



There are one or two aspects of this question of plant- 

 naturalisation which have not yet received much investiga- 

 tion, though they are very interesting. 



Often when a species is first introduced into a country 

 or district it exhibits most extraordinary vitality for a time, 

 and then appears gradually to lose its exuberance of growth, 



