Chap. IV] MOUNTAIN REGIONS IN TEMPERATE ZONES 761 



On exposed places in this upper part of the region dry stony tracts 

 prevail, which sometimes exhibit a poor steppe-like character, sometimes 

 bear at wide intervals thorny shrubs and scanty grass, but are chiefly 

 noted for some extremely peculiar xerophytes, species of Aciphylla and 

 Cclmisia. Aciphylla (Fig. 463) is a genus of Umbelliferae, and its species 

 develop a spherical mass of densely crowded, firm, ensiform leaves, from 

 a turnip-shaped root-stock. The Celmisieae (Fig. 464) are grass-like 

 Compositae, the structure of whose leaves exhibits a striking similarity 

 to that of steppe-grasses. No less remarkable in this formation is the 

 occurrence of ericoid shapes in genera in which this would not be expected, 

 namely, in Veronica cupressoides (Fig. 462) and in Senecio cassinioides. 

 All these forms, deviating from the systematic type, are products of the 

 dry climate ; that they originated from 

 normally shaped ancestors is shown by 

 the well-known fact that Veronica cupres- 

 soides and Senecio cassinioides produce 

 primordial leaves of quite different form, 

 and that broad leaf-blades are formed in 

 the Veronica when it grows in moist air. 



Above the forest appear elfin-wood and 

 shrub displaying usually a rich and dense 

 ramification, relatively thick boughs, the 

 rough bark of which frequently bears 

 small lichens, and composed of species 

 possessing with rare exceptions (Co- 

 prosma serrulata, Fig. 465, 1) very small 

 leaves of marked sclerophyllous structure. 

 Prominent among them are species of 

 the epacridaceous Dracophyllum (Fig. 

 465, 2), but especially Compositae be- 

 longing to the genus Olearia (Fig. 465, 3), and Senecio. Diels assigns 1,350 

 meters as the upper limit of the elfin- wood on the South Island. But it 

 frequently descends much lower, in river valleys even down to the sea-shore. 



Elfin-wood and shrub denote the commencement of the alpine region, 

 which begins remarkably low down in New Zealand. A low summer 

 temperature, and, in the east, dry winds, here reinforce the action of the 

 mountain climate. Rocks, and especially screes, termed ' shingle-slips,' 

 predominate in the alpine region, and frequently cover the mountain 

 slopes as far as the plateau. This texture of the soil owes its origin to 

 a true desert-weathering, that is, to the action of great variations in 

 temperature combined with dry air. We can in fact speak here of 

 a mountain-desert, as in the Andes, to the vegetation of which that of 

 the hieh mountains of New Zealand bears a great resemblance. As in 



Fig. 462. Veronica cupressoides. New 

 Zealand. Natural size. 



