58 MOUNTAIN AND MOORLAND 



with others of the same kind growing at lower levels, 

 an increase in the size of the flowers and in their 

 fragrance. 



One of the obvious features of the mountains is the 

 low temperature, especially at night and in the winter. 

 In relation to this we can understand the handicapping 

 of growth, which warmth up to a certain limit always 

 promotes. Plants constitutionally dwarfish will get 

 on best, and likewise those which are rather thick- 

 skinned. Perhaps a woolly covering may also have 

 some protective value, but are we not a little too apt 

 to think of plants in terms of our own constitutions 

 and clothing? 



A very important feature of the mountain climate 

 is its tendency to dry things up by the wind, by the 

 thin air, by the sun. Therefore mountain plants show 

 many adaptations towards preventing a dangerous 

 degree of transpiration of water. The leaves are 

 often leathery, especially in woody plants; others are 

 hairy, which lessens the loss of water-vapour; others 

 are varnished with wax; a few are succulent, with 

 stores of water for periods of drought. .Some alpine 

 plants meet the difficulty in another way, by having a 

 richly developed root system, going very deep, or 

 spreading far, or having many branches in the soil. 

 It must be remembered that the difficulty is twofold : 

 there is the drying-up tendency, and there is the low 

 temperature of the soil which lessens the capacity 

 that the roots have for absorbing water. 



Expressed technically, the difficulty that plants 

 living at high altitudes have to face is " physiological 

 drought." There may be plenty of water, but it is 

 not readily available when the temperature of the 



