28 NEW ZEALAND PLANTS. 
are confined, or almost so, to the coast-lne. The commonest of the 
latter are: Zostera, Spinfex, Atropis, Salicornia, Mesembryanthemum, 
Tetragonia, Spergularia, Euphorbia, Corynocarpus, Apium, Samolus, 
and Avicennia. The species of these genera are, for the mest part, 
dealt with farther on, and their popular names and characteristics 
are given. 
The species common both to the coast-line and farther inland 
are numerous enough. Their coming to the coast depends a good 
deal on the conditions offered both of climate and soil. Where 
there are true coastal conditions there are few non-coastal plants— 
that is, where the sea-wind strikes fair, brmging with it at times a 
considerable amount of sea-spray, or where a flat area is subject to 
the invasion of brackish water. 
The following inland plants, amongst others, are common in 
many places on the sea-coast: The kiekie (Freycinetia Banksii) ; 
the toetoe (Arundo conspicua); the toetoe-whatumanu (Mariscus 
ustulatus), as far south as Banks Peninsula and near Kumara 
in Westland; the tuhara (Cladium Sinclairw), im the northern 
part of the North Island only; the two species of New Zealand 
flax (Phormium tenax and P. Colensor); the tree-nettle, or onga- 
onga (Urtica ferox); the two pohuehues (Muehlenbeckia complexa 
and M. australis); the red and the white tea-tree (Leptospermum 
scoparitum and L. ericoides); the southern rata (Metrosideros lucida) 
in the south of the South Island and in Stewart Island; certain 
ferns—e.g., the common maidenhair (Adiantum affine), the common 
climbing-polypody (Polypodium diversifolium), and the thick-leaved 
polypody (Cyclophorus serpens). 
The chief factor operating upon coastal plants different from 
those to which inland plants are exposed is a greater amount of salt 
in the soil. This factor may easily be overestimated, since plenty of 
- soils close to the sea contain very little salt indeed. Other factors 
affecting the distribution and forms of the plants are frequent high 
winds (perhaps charged with salt), bright sunlight, and a mild climate. 
The effect of salt in the soil is reflected in the plant by succu- 
lence of stem, of leaf, or of both. Such succulence is found in 
plants exposed to excess of salt the world over. This succulence 
is caused by the presence of special tissues which serve for water- 
storage. Certain New Zealand coastal plants exhibit this feature. 
The ice-plant, or horokaka (Mesembryanthemum australe), which so 
