Oliver. — Vegetation of the Kerinadec Islands. 145 



to north-west, and is undoubtedly the result of hurricanes which visit the 

 islands occasionally and blow with great violence from the south-east. Rho- 

 palostylis Baueri and Cyathea Jcermadecensis are abundant, and charac- 

 teristic of wet forest. The principal trees are Melicytus immllorns, Ascarina 

 lanceolata, Nothopanax arhoreum, Coprosma acutifolia, and liapanea ker- 

 madecensis. In a deep gully on Bollons Peak a single tree each of Homo- 

 lanthus polyandrus and Boehmeria dealbata were noticed. 



In a limited sense the plants of the wet forest group themselves into 

 associations in which a single species is dominant. On Big Hill immense 

 Melicytus ramiflorus trees, each with numerous stems, are most plentiful. 

 On Expedition Hill and other places Ascarina lanceolata forms an association 

 of tall slender trees, 8 m. in height, bearing foliage and flowers at the top 

 only. 



But the most imjjortant and distinct of the subformations is that of 

 Cyathea kermadecensis. On Bollons Peak a large area is occupied by this 

 tree-fern, associated with a few forest-trees — Melicytus ramiflorus, Notho- 

 panax arhoreum, Ascarina lanceolata, and Metrosideros villosa. The tree- 

 ferns are growing close together, and average about 20 m. in height. The 

 bases, composed of adventitious roots, are 1-2 m. in diametei, and often 

 three or four unite, forming a mass 3 m. or 4 m. through. Lying about 

 the ground are numerous fallen trunks of tree-ferns and trees, all covered, 

 like the standing tree-ferns, with mosses and fems. The tree-fern trunks 

 are thickly clothed with Hymenophyllum demissum, Trichomanes venosum, 

 Asplenium flaccidmn, A. caudatum, Polypodium diversifolium, and mosses, 

 Pteris comans and Dryopteris glabella form what little undergrowth 

 there is. 



The luxuriant growth of epiphytic vegetation is the main feature which 

 stamps the physiognomy of the wet forest. A third of the species of plants 

 noted in wet forest are epiphytes, and only two of this number (11) also 

 occur there on the ground. The trunks and branches of forest-trees and the 

 stems of tree-ferns and palms are clothed with mosses and ferns. Even 

 where the forest-floor is bare of vegetation, epiphytes are not any the less 

 abundant. 



Leaning trunks and horizontal branches of trees collect a lot of soil, 

 on which several kinds of mosses and Uchens, as well as a variety of 

 ferns and two spermophytes, flourish. The following were observed in 

 such situations : Polypodium diversifolium, Cyclophorus serpens, Asplenium 

 flaccidum (two forms), Lycopodium Billardieri, Acianthus Sinclairi, Pepe- 

 romia Endlicheri, Hymenophyllum demissum. 



The trunks of tree-ferns are erect but rough. As a substratum for 

 plants they become very dry in fine weather, while no soil was observed 

 to collect on them. In the wet forest they are nevertheless invariably 

 clothed with various species of mosses, Hymenophyllum demissum, Cyclo- 

 phorus serpens, Asplenium caudatum, A. flaccidum ^two forms), and Tmesi- 

 pteris tannensis. 



On the under-side of leaning fern-trunks where rain-water does not flow 

 none of the above plants occur, but in such places Trichomanes venosum is 

 found. It alone appears to be able to obtain sufficient moisture from the 

 atmosphere to sustain life, while in places exposed to the weather it is 

 apparently not able to hold its own against more hardy ferns. 



Palm-stems, being smooth, do not afford stations readily occupied by 

 epiphytes. In wet forest, however, they are usually clothed with mosses, 

 Polypodium diversifolium, and Cyclophorus serpens. 



