Cockayne. — Plant Geography of the Waimakariri. 121 



them, on, e.g., the final rocky precipices of a mountain peak. 

 These examples may give some idea of the climate that the 

 plants of this region must endure in many instances. 



To the above conditions of soil and climate the plants have 

 responded in various ways. The details of such adaptations 

 will be entered into more fully when dealing with the con- 

 stituents of the formations ; here it is only necessary to point 

 out a few of the more common adaptations assumed by plants 

 frequently enough to affect the general plant physiognomy of 

 this region. 



Where constant and often furious winds blow it is neces- 

 sary that the plants should protect themselves in some way or 

 another from being broken or torn to pieces. But such winds, 

 besides acting in this mechanical way, also indirectly exercise 

 a niost powerful physiological effect upon plant-life by causing 

 excessive transpiration. And how enormous must such tran- 

 spiration be during a hot nor'-wester ! That plants even when 

 frozen can be killed by excessive transpiration is pointed out 

 by Schimper (lob. cit., p. 45), Nor is such transpiration con- 

 fined to leafy plants ; even deciduous trees in the cold winter 

 of Michigan, U.S.A., may be damaged through excessive 

 transpiration through the bark (Bailey, loc. cit., pp. 13-18). 

 Bearmg these facts in mind, the cold high winds of winter 

 must also have a powerful influence upon plants. 



Many of the commonest forms of our plants are adapta- 

 tions against the effect of wind, and serve at the same time 

 both to resist its violence and to reduce transpiration in many 

 cases to its smallest limit. Keduction of transpiration is also 

 controlled by other means, to be treated of in due course. 

 One very common form which meets the end in view is a 

 round ball-like growth of the entire plant, and is to be seen in 

 great perfection in numbers of shrubby plants — e.g., Veronica 

 traversii, Hynienanthcra alpina, T. Kirk (var.), and Plagi- 

 anthus divaricatus, this latter growing in salt meadows, a 

 station physiologically dry. In the cases cited the very close- 

 growing, divaricating, often intertwining branches shelter very 

 considerably both themselves and their leaves, presenting a 

 surface which the wind cannot damage, and so ball-like are 

 many — e.g., Veronica odora — that they look as if trimmed into 

 that shape purposely by a gardener ; indeed, few things are 

 more strange than to see a clump of these perfectly globe- 

 shaped bushes with their varnished green leaves, the whole 

 looking like some portion of a cultivated shrubbery, away up 

 a distant river-bed, where man may never have set foot before. 

 Even in sheltered places in cultivation these plants still main- 

 tain this habit, which is evidently quite hereditary. The well- 

 known tussock form of certain grasses and sedges serves the 

 same purpose, and is a most distinguishing form of the entire 



