Cockayne. — Observations on Coastal Vegetation. 323' 



spread,* and it is hard to believe that the Australian Styphelia 

 richei did not reach the above group by way of New Zealand 

 originally. 



7. Southern and Northern Ijmits of Coastal Plants. 

 The coastal formations consist, as is shown further on,, of 

 two classes of plants — viz., the coastal plants proper, and those 

 which are common inland. Now, although the strictly coastal 

 plants are usually of vdde distribution, not only in the South 

 Island, but through much of the New Zealand biological region, 

 some are confined to a small area, and others again only reach 

 a certain distance to the north or the south, as the case may be. 

 Consideriiig first this latter category, the question is at once 

 opened up as to the reason why certain plants have a definite 

 northern and southern limit. This inquiry is much easier to 

 propound than to answer in the present state of knowledge. 

 At first sight the matter under consideration might seem merely 

 to be a question of cUmata — that when, say, a northern plant 

 of a frostless climate reached a point where frost occurred, it 

 could advance no farther ; or such a plant, again, might require 

 for its well-being a certain average maximum of heat. But an 

 examination of the facts shows that there is something much 

 more far-reaching in the matter than the above ; but this can be 

 best understood by citing some specific examples. Take, first 

 of all, the case of the kauri {Aqathis ausiralis), which, although 

 not a coastal tree, may fairly be used as an example, since the 

 matter under consideration concerns the whole New Zealand 

 flora, while the kauri, moreover, is one amongst a number of 

 plants which are confined to the north, roughly speaking, of 

 the 38th parallel of latitude. Now, south of this line for a con- 

 siderable distance, especially on the west of the North Island,, 

 there are no climatic conditions which should inhibit the 

 growth of this tree in many places. Moreover, at Wellington, 

 more than 3 degrees to the south of the kauri limit, this tree 

 grows famously in cultivation, producing cones regularly. Even 

 at Christchurch, in the South Island, in the Domain, where 

 — 9° C. has been frequently recorded, the kauri grows well and 

 has recently fruited. Also, a young plant has withstood the 

 cold cf this winter in the garden of the biological laboratory,. 

 Canterbury College, in a position where it could get no sun, and 

 where a plant of Veronica elliptica collected by me in Campbell 



* G. M. Thomson is also of opinion that this plant must have formerly- 

 existed in New Zealand, and he suggests that it may have died out or 

 been " eaten out by some more recent form of animal life, perhaps by 

 moas, which were formerly enormously abundant, and were vegetable- 

 feeders " (43; p. 315). 



