FOREST OF THE KERMADECS. 145 
the latter the Mariscus and its associates again occur—one and the 
same association owing its distribution to two distinct causes, one 
geological, the other biological. 
A rather important plant-association is the girdle of ngaio scrub 
along the coast, especially where there is a space for its occupation 
and development between the cliffs and high-tide mark. The 
principal members are—the ngaio (Myoporum laetum), the kawa- 
kawa (Macropiper excelsum var. major), the climbing-gourd (Sicyos 
australis), the mariscus-sedge (Mariscus ustulatus), the leguminous 
Canavalla obtusifolia, Carex semi-Forsteri, the fern Pteris comans, 
and, close to the sea, tussocks of Scirpus nodosus. 
By far the most important plant-formation of the group under 
consideration is the forest, which falls into two associations—viz., the 
one where the driest conditions provided rule, and the other occurring 
at higher elevations, where the climate is wetter. Dry forest is dis- 
tinguished by the presence of Metrosideros villosa as the dominant tree, 
whereas in wet forest no special tree is dominant. The more im- 
portant trees and shrubs of the Kermadec forest are the following : 
Metrosideros villosa, a tree 70 feet high or more (aerial roots pass off 
from the lower part of the trunk and finally enter the ground and 
function as stems); the karaka (Corynocarpus laevigata), also a tall 
tree; the ngaio (Myoporum laetum), equal in height to the other tall 
trees ; the mahoe (Melicytus ramiflorus), a small tree in dry forest but 
a massive bushy tree where rain is abundant; the endemic Rapanea 
kermadecensis, a small tree; the endemic Ascarina lanceolata, a tall 
shrub or small slender tree ; the wharangi (Melicope ternata), a small 
tree with leaves larger than those of the same species in New Zealand 
proper; the endemic Coprosma acutifolia, a small slender tree; the 
Kermadec nikau (Rhopalostylis Cheesemanir). The two endemic tree- 
ferns are often in abundance, Cyathea kermadecensis, 70 feet high, 
sometimes making extensive colonies in wet forest (fig. 91), while 
C. Milnet is more characteristic of dry forest. 
It will be seen from the above brief account of the forest that 
the warm, humid climate of the Kermadec Islands, to which the 
forest owes its existence and luxuriance, is reflected also in the 
luxuriant growth of certain trees—eg., the karaka (Corynocarpus 
laevigata), the mahoe (Melicytus ramiflorus), and the ngaio (Myoporum 
laetwm)—which far exceed the height they attain in New Zealand. 
