Ecological Botany.] SUBANTARCTIC ISLANDS OP NEW ZEALAND. 215 



natural bridges over the deep depressions of the forest-floor. From these trunks, 

 which are quite irregular in form, pass off others twisted in every way conceivable, 

 and frequently forming a complete and rigid tangle (fig. 10). Ultimately certain 

 branches arise, which, bending upwards, sometimes at a right angle, rise to a variable 

 height, and, branching again frequently, the erect stems become closer and closer, 

 and at the same time more and more twiggy. Wide spaces extend between the 

 spreading and diverging branches, but above, where the growth is erect as in any 

 normal tree, only small patches of light are visible, each primary branch having its 

 own set of twigs and leaves, but the whole coming together and making a continuous 

 and flat roof. 



The trunks are reddish-brown in colour, and long strips of papery bark depend 

 from them. Sometimes there is little undergrowth, and nothing meets the eye save 

 the horizontal or arching trunks and the bewildering network of twisted branches 

 (fig. 10). At other times there is a close undergrowth. Here may be a colony of the 

 fern Pdystichum vestitum, the dark-green coriaceous fronds 1 m. or more in length 

 spreading outwards from the summit of a stout trunk 1 m. to 1 -5 m. or more tall. 

 Near the shore many metres of the forest-floor will be covered with close masses of 

 the ferns Blechnum durum and Asplenium obtusntum, and a few plants of Stilhocarpa 

 folaris will be present. In other parts the various forest trees and shrubs may occur 

 in plenty, and then, particularly when Suttonia divaricata is abundant, the forma- 

 tion, what with the obstacles offered by the prostrate trunks and divaricatingly 

 branched shrubs, becomes almost impenetrable. The floor, too, is rarely level ; 

 usually there are deep hollows and depressions everywhere, and these increase the 

 difficulties of progress, which is best made along the paths formed by the hair-seals. 



The close roof leads, even during the most boisterous days, to a comparatively 

 wind-still atmosphere beneath, in consequence of which marked hygrophytic con- 

 ditions prevail. Without, transpiration may be intense ; within, all is suitable for 

 the most pronounced moisture-demanding plants. And so there is a wonderful 

 wealth of filmy ferns, mosses, liverworts, and great foliaceous lichens. The first 

 named form sheets of delicate green both on the ground and the tree-trunks. The 

 bryophytes build up cushions both on forest-floor and tree-trunk, or cover the 

 latter with a close thick mantle, through which the slender rhizomes of the filmy 

 ferns ramify, and which can be stripped off in compact sheets. The yellowish moss 

 Dicranolotna Billardieri, and the liverworts Plagiochila ramosissima and Masti- 

 gohryum involuium are conspicuous cushion-builders. The dark - green Aneura 

 multifida forms many extensive flat patches on the forest-floor. The beautiful 

 SchistocMlfi Lehmanniana and the handsome yellowish Trichocolea tomentUla make 

 extensive colonies in moist places. On the trunks the mosses Ptychomnium acicidare, 

 Lembophi/llum cochlearifolium, and Stereodon chrysogaster occur in large masses. 

 Usually the various bryophytes grow so mingled together that in gathering a 

 specimen a number inextricably mixed are collected, some of the more minute living 

 on the larger ones or on the moss cushions. 



To the peat-forming capacity of the mosses and liverworts during the course of 

 many generations is due much of the irregularity of the forest-floor, and even the 

 deep hollows may be attributed to this cause rather than to the action of water. 

 Polypodium diversifolium, with its dimorphic, coriaceous, broad, green leaves, and 

 thick moisture-holding rhizome, is very abundant both as a ground-plant and a liane, 



