264 The Vegetation of the Subantarctic Islands. 
„Forest. 
A very considerable part of vr the main island and Pitt Island is occupied 
‚ by forest of which there are two classes, viz. lowland and upland; the first 
distinguished by the dominance of Corynocarpus and an abundance of Rhopalo- 
stylis and Olearia Traversi, and the second by the. absence of the above 
three trees, the dominance of Senecio Huntii and Dracophyllum arboreum, and, 
with the exception of Veronica gigantea, a smaller percentage of the other 
forest-trees than in the lowlands. Shrubs, such a common feature of New Zealand 
rain-forest, are absent, and the tallest undergrowth consists mainly of the 
5 tree-ferns (Dicksonia squarrosa, D. fibrosa, Cyathea Cumninghamii and C.- 
medullaris) and, in some localities, the stems of the liane Rhipogonum. On 
the floor, are many of the usual Nas Zealand forest-ferns. The lowland forest 
is generally quite low (6—ı3 m) and the roof is flat and close, the trees being 
of equal height. So too, is upland forest low and flat-roofed, except where 
D. arboreum raises its needle-like foliage above the general evel. Filmy ferns 
occur in both classes of forest, but they are most abundant in the upland and 
may carpet the ground or hide the tree-trunks or fern-trunks. Forest on limestone 
| near the large lagoon is distinguished by the presence of Sophora chathamica, 
= absent elsewhere. 
ne, ne 6. Heath. 
ri exposed situations heath succeeds moor as the ground nal becomes 
fairly dry, or, in many places at the present time, it has seized the ground 
from which forest has been eradicated by fire. There are two classes of the 
| TORIERREIRAE, shrub-heath and bracken-heath. 
I. b-heath is distinguished by the presence of the ericoid shrubs Sty- 
0 Phelia Richei and S. robusta, the rush-like Scirpus nodosus and the Iris-like 
 Libertia ixioides. Pimelea arenaria, or an allied species, is common insome 
places. Other species are: — Pieridium esculentum, Calamagrostis Forsteri, 
anthonia semiannularis, Acaena novae- zelandiae, Pratia arenaria, Heli 
6 chrysum EEE and raphalae Japonicum. 
00 Bracken-heath frequently consists of pure Pteridium ion foraning 
dense thickets and attaining a height of more than 1.5 m where more open, 
various plants of AR. ‚gain a Be and Tthere are transitions between 
& Br Se associations. x 
