xiv INTRODUCTION 



But there are other points of structure besides the 

 colour and brightness of the flowers in which alpine 

 species show characteristic differences from their lowland 

 cousins. The summer, the period of the ripening of the 

 seeds, is short ; consequently but few species are annual, 

 and therefore entirely dependent on seeds for their pro- 

 pagation. The root-system is, as a rule, strongly deve- 

 loped ; both in order to afford sufficient protection against 

 the prevalent strong winds, and for the purpose of draw- 

 ing as large an amount of nutriment as possible from the 

 scanty soil. On the other hand, in the parts above the 

 surface of the soil the development of woody tissue is 

 often but small. The leaves are protected in various 

 ways against excessive transpiration or evaporation of 

 moisture from the hot summer sun. They are often 

 very crowded (caespitose), or are covered with a dense 

 felt of hairs ; or they are thick and fleshy, their tissue 

 being permeated by canals and chambers containing 

 water. The very early period of flowering of many of 

 the most beautiful species is due to their almost invariably 

 perennial character. The plant has not to spring up from 

 seed and then to produce its buds and flowers ; the flowers 

 are already there, formed during the preceding summer, 

 and gradually developing beneath the friendly covering of 

 snow, ready to expand as soon as the April zephyrs call 

 them forth from their hiding-place. Further evidence 

 that the alpine flora is the result of adaptation to climatic 

 conditions is afforded by the fact that, within the bounds 

 of what must unquestionably be regarded as a single 

 species, individuals change in character as we ascend to 

 higher altitudes, the leaves becoming more hairy or more 

 fleshy, and the flowers brighter or larger. Professor G. 



