Cockayne. — Obserrations on Coastal Vegetation. 327 



this line many of the northern species and genera are wanting, 

 but a large proportion extend south, some just crossing Cook 

 Strait, others finding their southern limit at Banks Peninsula, 

 or at other definite points east and west, while others, again, 

 extend right to Stewart Island and even to the Southern Islands. 

 In the same way the subantarctic element, including in this some 

 of the endemic genera — e.g., Cdmisia, Olearia, Aciphylla — has 

 pushed northwards, leaving here and there outposts or settle- 

 ments cut off from the main body, such as the Crassula moschata 

 at Island Bay, Wellington, before mentioned, but especially the 

 patches of Notkofagus in northern Auckland. Generally speak- 

 ing, in this struggle the subtropical element is the conqueror, 

 the subantarctic plants being driven into the more unfavourable 

 stations, such as lowland bogs, the subalpine region where pure 

 Nothofagus forests flourish, or alpine heights. 



As to how finally the various combinations of plants have 

 come about w^hich make the formations and associations, it 

 seems in the present state of knowledge vain to inquire. The 

 action of minor climatic changes is but little known. Our ignor- 

 ance is great regarding the mutual reactions of plants on one 

 another when brought into contact, reactions which must have 

 much to do in determining what plants shall finally occupy a 

 station. In this matter experiment is imperative, and a fruitful 

 field is open in New Zealand, where, wdth the i)itroduction of 

 so many exotic plants and animals, unpremeditated experiments 

 are even now in progress everywhere. 



Finally, to sum up the matter, all that can be said about the 

 distribution of the New Zealand coastal plants is thttt it is the re- 

 sultant of a large number of causes. The historical factor and evo- 

 lution determine the species, climate and soil sort them out into 

 groups, and the struggle for existence, which is governed by the 

 life-forms and constitutions of the competitors, finallv fixes the for- 

 mation — that is, so far as a formation may be termed a fixed eiitity. 



8. Local and Limited Distribution. 

 Coming now to those plants mentioned above as being con- 

 fined to a small area, the following citations must suffice, but 

 these include some of the most striking amongst New Zealand 

 plants : Helichrysiim purdici occurs, so far as is known., only 

 in one or two stations on the north shore of the Otago Harbour, 

 and there are only a few plants in each locality. I found by 

 cultivation that this plant would not endure much frost. Olearia 

 insignis, so far as its coastal distribution is concerned, is limited 

 to cliffs on the Marlborough coast,* and it is sometimes accom- 



* Inland it is frequent on rock - faces, and it ascends to the alpine 

 region in the Kaikoura Mountains. 



