New Zealand Plants and their Story
Adaptations of the Alpine Plants
Adaptations of the Alpine Plants.
Fig. 49.—Veronica spathulata, growing on scoria desert, base of Ngauruhoe.
Lands Department.] [Photo, L. Cockaync.
Fig. 51.—Helichrysum bellidioides, showing the white bracts of the flower-heads, which look like petals. Stony ground near Arthur's Pass.
[Photo, L. Cockayne.
Roots of an extraordinary length form an excellent provision for obtaining an abundant water-supply at all seasons, and these are very frequent amongst the alpine plants. But, above all things, the leaf, in structure and form, shows drought-resisting contrivances. The most common of all is a mat of hairs on the under-surface of the leaf, so characteristic of the celmisias (fig. 43). Some, again, such as the Aciphyllas* (spear-grasses), have extremely rigid, vertical leaves, which both resist the wind and can never receive the direct rays of the sun.
Perhaps the most interesting feature of the New Zealand alpine plants, and one which is not so well marked in the alpine plants of Europe, but is seen in those of the Andes, is the capability of one portion of the living plant to turn into peat, while its remaining part grows vigorously, and even uses its own dead self as food material. This habit is not specially in harmony with an alpine climate, but rather with absence of sunlight and prevalence of rain and mist—just such a climate as exists in the subantarctic islands to-day. Most of the celmisias are surrounded at the bases of their leaves by quite a thickness of rotting leaves, and the same may be seen in a very large percentage of the New Zealand alpine plants. Such an adaptation perhaps indicates that our alpine flora originated not on the high mountains at all, but in the sunless and wet regions of the south.page 104
Fig. 52.—The Dwarf-pine (Dacrydium laxifolium), which on the dry pumice soil has assumed the cushion-form Veronica tetragona, a Whipcord-veronica growing on it above, and small plants also of Celmisia longifolia. Volcanie plateau of North Island, at 3,700 ft. altitude.
Lands Department.] [Photo, L. Cockayne.
* In this book the plants generally referred to Ligusticum are included in Aciphylla. In this sentence only Aciphylla in the more restricted sense is intended.