128 



Transactions. — Botany. 



except in river-beds and their vicinity and on the mountain 

 passes. Streams are often abundant. As an example of the 

 great permeabiHty of the soil with regard to water, I may 

 mention that the water of a waterfall of considerable volume 

 descending from the eastern slopes of Mount Torlesse sinks 

 completely underground at a few metres below the fall, while 

 at a few metres above there is also no sign of water, except 

 during heavy rain. In this case the water-channel is very 

 steep. Kaka Creek, at the base of Broken Hill, behaves in a 

 similar manner ; indeed, for the water of a river suddenly to 

 disappear through its shingle is of quite common occurrence 

 in all the South Island mountains. The chief plant-formations 

 of this region are : — 



The Fagus forest descends into the montane region, where 

 it often occurs on the shady side of river-terraces sheltered 

 from the north-west. The shingle-slip to be mentioned in the 

 next subregion also frequently descends into this. Several 

 smaller formations will also be considered. 



(4.) The Alpine Eegion : This extremely interesting and 

 important region extends from 1,220 m. to 2,134 m. It in- 

 cludes all that portion of the mountains which lies above the 

 winter snow-line, consequently its plants undergo pressure 

 by the snow and exclusion from light unknown to those of 

 lower regions. The rainfall is certainly greater than that of 

 the subalpine zone, and the wind on the exposed portions of 

 the mountains much stronger. Prost will be more severe 

 than in the subalpine region, but no statistics exist on this 

 head as yet with regard to New Zealand. According to 

 Schimper (loc. cit., p. 727), the air-temperature decreases at 

 the rate of 0-58° C. for each 100 m. This would give a differ- 

 ence of 5-2° C. or 9-3° Fahr. between the temperature of the 

 highest and lowest parts of the region, so far as the air was 



• These will include several minor formations, differing in great mea- 

 sure upon the amount of stagnation of the water. 



t The plants of wet rocks, of course, differ from those of dry rocks, so 

 here some minor distinctions will have to be drawn. 



