352 Transactions. 



Here we fiiid that the woody plants of Britain — a region glaciated within 

 recent geological times — constitute only 74 per cent, of the whole flora. 

 Of the ninety-one woody plants in Britain, excluding prostrate and creep- 

 ing species, sixty-five, or 71-4 per cent., are quite deciduous. The remain- 

 ing twenty-six species are evergreen, but their foliage is of such a character 

 that they are not liable to take any damage from snow. I append a list of 

 these forms,* from which it will be seen that some of them are small-leaved 

 heaths and similar plants. 



New Zealand has 1,415 species of plants, but 450 of these, or 31-8 per 

 cent., are woody. Of this number, no less than 398, or 88-3 per cent., are 

 evergreen ; forty-five, or 10 per cent., are leafless or have only minute ap- 

 pressed leaves ; while seven species, or less than 1-5 per cent., are moie or 

 less deciduous. These are Gaya Lyallii, which is deciduous only at high 

 levels and in the south end of the South Island, but is evergreen in the 

 valleys of Nelson and Westland ; Aristotelia racemosa. A. Colensoi. and 

 A. fruiicosa. which are also deciduous only at high levels ; Coriaria thy mi- 

 folia, also tending to become deciduous at high levels ; and Fuchsia ex- 

 corticata and F. Colensoi, which are deciduous at least in the southern part 

 of New Zealand. Thus in the whole of New Zealand there is no absolutely 

 deciduous species ; and this is, to my mind, a strong argument against recent 

 glaciation. 



III. 



A characteristic featuie of the flora of New Zealand is the presence of 

 a large xerophytic element, a very considerable group of the plants being 

 specialised to endure desert conditions. 



All green-leaved plants are furnished with stomata for the breathing 

 in and out of the gases which they feed on and eliminate, and for the trans- 

 piration of water- vapour. Plants growing in peaty moorlands, and such 

 as grow on the sea-coast, even in climates where there is relatively con- 

 siderable humidity, are frequently specially modified to resist overtrans- 

 piration, and these modifications take the form of archings of the upper 

 surfaces of the leaves, thickening of the tissues, and diminution of the 

 number of stomata on all their breathing-surfaces. Eliminating these 

 locally modified plants, which are common to many regions of the globe, 

 we find in New Zealand, and especially on the eastern side of the Alps, and 

 the hills and plains lying to the east of the dividing-range, an assemblage 

 of plants — approximately estimated by me at 220 species — which are 

 peculiarly adapted to withstand drought. Their breathing-surfaces are 

 more or less covered with hairs, sometimes produced in extraordinary pro- 

 fusion, or they have greatly thickened epidermis with deep-set stomata, 

 or the upper surfaces which have no stomata arch over and thus tend to 

 close the pores on the sheltered undersides. In many the leaves become 

 modified {e.g., many species of Veronica), so as to lie closely pressed against 

 the stem, or the leaves are more or less completely aborted {Discaria tou- 

 mato}( and species of Carmichaelia). the breathing-pores in such cases being 

 produced on the epidermis of the branches and stems. 



* Berberis vulgaris, Ilex aquijolhim, Euonymus europceus. Genista tin-ctoria, Vlex 

 europceus. U. nanus, Cytisus scoparius, Hedera Helix, Vaccinivm Myrtilhis, Arbutus 

 Unedo. Andromeda poUjolia, Erica Tetralix, E. cinerea, E. ciUaris, E. lagans, E. rnedi- 

 terranea, Calluna vulgaris, Phyllodoce cceridea, Ligustrmn rulgare. Daphne Laureola. 

 D. Mezereum, Hippophce rhamnoidcs. Viscinn album, Pinus si/lvestris, Juniperus cornmvnis, 

 Taxus baccata. 



