Cockayne. — Obsercations on Coastal Vegetation. 311 



the sea, ever in the most wii\d-swept localities,* if the\^ are af- 

 forded shelter — i.e., if the wind factor be eliminated. The seeds of 

 many maritime plants are easily capable of spreading inland by 

 various means, and yet there is the comparatively large number 

 (94) of species which are confined exclusively to the coast. All 

 the above points distinctly to the supposition that the coastal 

 plants as a whole occupy their peculiar station not from choice, but 

 from necessity, and that they are ordinary inland plants which have 

 been driven out of the more hospitable ground by better-equipped 

 competitors. Of course, hadng finally settled down in a halo- 

 phytic or psamniaphytic station, it goes without sa)dng that 

 such plants would in some instances, in course of time, develop 

 those special adaptations which distinguish coastal plants. 



Certain inland xerophytes (see list in. Section 16) which 

 commonly grow under coastal conditions owe their position to 

 their xerophytic structure and the abuiularce of room offered 

 in the open coastal formations for phnit-colonists. It is easil} 

 conceivable that if certain causes changed the condition of 

 existence for such inland xerophytes, the plants of the coast 

 might be the sole survivors. In this way, too, without any 

 special competition with other plants, coastal species may have 

 originated. Such, in one instance, I have shown to be the 

 case in Chatham Island, where Phorniinni tenax, formerly a most 

 common plant, is day by day becoming restricted to a few 

 special stations owing t(» the attacks of domestic animals ajid 

 drainage (12). 



19. Some Dipperenoes between North Island and South 

 Island Coastal Vegetation. 

 Before concluding, a few words seem desirable on certain 

 general differences which exist between the coastal vegetation 

 of the North and South Islands. As already pointed out, the 

 coastal vegetation proper of the South Island does not com- 

 mence until parallel 42° S. is crossed, this being, however, a by no 

 means rigid line of demarcation. To the north of this limit the 

 formations are closely related to those of the southern part of 

 the North Island. It is therefore between the vegetation of 

 the northern and southern floristic provinces that a comparison 

 may be drawn, rather than between the two Islands as a whole. 

 These two provinces, even on the coast, are more or less different 

 in many ways, but these differences have a twofold origin, the 



* At New Brighton, Canterbury, a garden sheltered by a ]ialing fence 

 lias been for some years on the actual shore, and many kind.s of ordinary 

 gaiden plants thrive excellently. The gardens of the lighthouse-keepers, 

 where excellent vegetables are raised, are admirable examples of the same 

 kind. So, too, are the many inland European plants which now grow 

 naturalised clo.'^e to high- water mark so frequently. 



