20 INTRODUCTORY 



which can transpire in some degree, are also clothed 

 with a coat of hairs, shows how necessary it is to 

 I stop every leak from which water might evaporate. 



A nearly parallel effect would be arrived at by 

 wrapping the plant in cotton- wool. The air entangled 

 in the meshes of the wool, or, in the case of the 

 Edelweiss, between the matted hairs, checks excessive 

 transpiration, the passage of the water- vapour being 

 hindered. Transpiration, or loss of moisture, must 

 of course go on to some extent, but the necessity 

 j in this and other plants, growing under very dry or 

 - desert conditions, is to check excessive transpiration. 

 Among plants growing under these conditions, many 

 different means are found by which this end is 

 attained. In the Edelweiss it is effected by the 

 covering of hairs, whereas in the Alpenrose, where 

 the same necessity exists, though in a much less 

 marked degree, the nature of the adaptation is 

 entirely distinct. 



The Edelweiss is found widely distributed in the 

 mountains of Southern Europe, not only in the Alps, 

 but in the Pyrenees, the Tyrol, and the Carpathians. 

 It is also abundant in India in the Himalayas. It is 

 a small genus of some six species, all essentially 

 Alpine plants, though closely related to the Cudweeds 

 {Gnaphalium) of the plains of Europe. Other 

 species of Edelweiss are found in Japan, Bolivia, 

 Tasmania, and Northern Asia, so that the genus 

 Leontopodium is widely distributed. 



Before leaving the Edelweiss, we may briefly notice 



