Cockayne. — Observations on Coastal Vegetation. 329 



down, and a second growth, easily mistaken for a primitive one, 

 now occupies the ground. An actual sea-beach may be occu- 

 pied exclusively, or almost so, by introduced plants. Thus the 

 steep, unstable gravel beach at Kaikoura abounds with Sherardia 

 arvensis and Scandix pecten-veneris, the only indigenous plant 

 present being Rumex ohtusij alias* The effect of drainage mav 

 be well observed where such operation has been carried on in 

 a salt meadow, the native plants decreasing as the ground gets 

 drier, and finally introduced grasses being dominant. Even 

 slightly brackish water is not free from the foreign element, 

 the customary dense red mat of Azolla having to give place to 

 Glyceria fluitans, or to the watercress, Nasturtium officinale. 



10. Mountain Plants on the Coast. 



There is at times a close ecological resemblance between 

 some coastal plant formations and those of higher altitudes. 

 This is probably owing to the fact that somewhat similar cli- 

 matic and edaphic conditions are provided. Alpine plants must 

 in many instances have been driven into the mountains by a 

 more vigorous lowland vegetation, such as lowland mixed forest 

 or tussock meadow, and where these formations cannot exist — 

 e.g., owing to sea-breezes, halophytic conditions, or a too scanty 

 supply of soil, such as rocky places or a gravel beach provide — 

 then subalpine or alpine plants, or those ecologically related 

 to such, may find a haven of refuge. Tho Olcuria insignis forma- 

 tion alluded to above is an excellent example, since it not only 

 occurs on cUffs facing the ocean and lapped by the waves, but, 

 with few members added or changed, it ascends high into the 

 mountains. Claytoyiia australasica, a plant of stony, subalpine 

 river-beds, shallow running water, and alpine shingle - slips, 

 descends to sea-level on sandhills near Dunedin (37 ; p. 544), 

 and also on the shores of Foveaux Strait. Helichrysum selago, 

 a shrub of subalpine and alpine rock-faces, occurs on ancient 

 sea-cliffs near Cape Saunders, Otago Peninsula. In the West 

 Coast Sounds, Cordyline indivisa, a plant of subalpine or mon- 

 tane forests, is not infrequent on clifis quite near the water's 

 edge. Coastal scrubs, as I have pointed out elsewhere, are 

 frequently closely related to subalpine scrub, both ecologically 

 and floristically. Finally, to quote an easily observed North 

 Island example, certain shady cliffs near Island Bay, Cook 

 Strait, have a fairly rich vegetation of Phormium cookianum, 

 Aciphjlla squarrosa var., Senecio lagopus, and a broad-leaved 



* See also Kirk's remarks on this subject (34a; p. 18). 



