Oliver. — Vegetation of the Kermadec Islands. 137 



actually raining, and between showers may even be suffering from the 

 desiccating effect of the wind. 



The forest, then, may be divided into two main types, determined by 

 the amount of moisture received. To these I apply the terms " dry " 

 and " wet." I might also refer to them as " upper " and " lower " ; but, 

 though the wet forest is confined to the upper parts of the island, its existence 

 as a distinct formation is not due directly to its altitude, but to its abundant 

 supply of moisture. 



Generally speaking, the wet forest occurs on ground more than 250 m. 

 above sea-level, though no sharp line of demarcation can be drawn between 

 the wet and dry forests, the one passing gradually into the other at an alti- 

 tude varying between 200 m. and 300 m. It differs from dry forest in its 

 much more luxuriant growth, and in the abundance of cryptogamic epi- 

 phytes. 



(6.) Leading Physiognomic Plants and their Life-forms. — (1.) Trees and 

 shrubs : Metrosideros villosa occurs in two principal forms. Its ordinary 

 state is a lofty forest-tree, 20 m. tall, with an erect, more or less crooked 

 or twisted trunk ^1 m. in diameter at the base, and branching, chiefly in 

 its upper part, in a most irregular manner. Aerial rootlets are usually 

 given out from the lower part of the trunk. These grow downwards, in- 

 creasing in size and branching till they reach the gTound, where they take 

 root, and, still growing larger, act like additional stems. 



The larger trees on the ridges and in exposed places usually have im- 

 mense prostrate trunks, sending up several branches each the size of a large 

 tree. Aerial roots are given off from the under-side of the trunk until the 

 base of the tree becomes a mass of entangled roots and stems of all sizes. 

 In leaning trees they form supports for the trunk, which thus spreads in the 

 direction in which it is leaning — usually downhill or in a northerly direc- 

 tion — that is, away from the point whence come the hiirricanes.* 



Corynocarpus Icevigata is a lofty forest-tree, 20 m. tall, with one to three 

 erect stems, branching chiefly about 8-10 m. above the ground. The three 

 trunks of one tree measured 115 cm., 135 cm., and 150 cm. in circumference 

 respectively. Bark dark brown, rather rough, with small lenticels. Foliage 

 dense. 



Myoporum loetum is a lofty forest-tree, 20 m. tall, with a trunk 2 m. 

 in circumference at the base, branching near the top, and with lax fohage. 

 Bark rough, grey. Leaves serrate, light green, pellucid glands scarcely 

 visible. Usually in the forest Myoporum Icetum is a small tree of the second 

 tier, with an erect stem and lax fohage. 



Melicytus ramiflorus in dry forest is usually a small tree with an erect 

 branching stem and lax foliage. In wet forest, however, it is a tree of large 

 proportions, consisting of a great many stems spreading from the base, 

 and with the moderately dense fohage borne principally at the top. Bark 

 nearly smooth, and of a light-gTey colour. 



Rapanea kermadecensis is a small glabrous tree, 6-10 m. tall, with an 

 erect stem bearing numerous horizontal branches. Bark rather smooth, 

 with small lenticels, reddish-grey. Wood extremely hard. Foliage dense. 

 Leaves elliptic-oblong, coriaceous, dark green, margins wavy, more or less 

 rolled; lamina? 42 x 20mm., 45 x 25mm., 60 x 27mm., 70 x 33mm. 



* Dr. Cockayne is of opihion (Report Bot. Surv. Stewart Island, 1909. p. 10) that 

 Metrosideros lucida has under certam stimuli an hereditary tendency towards a prostrate 

 habit. 



