THE EDELWEISS 19 



what appears at first sight to be a single head. 

 Thus, what is apparently a single flower is really a 

 very complicated structure. There is a large central 

 head, composed of many flowers and equivalent to 

 the inflorescence of a Daisy or a Sunflower, sur- 

 rounded by a varying number, usually five, of other 

 smaller heads, the whole being wrapped round by 

 woolly leaves which are called bracts. These 

 bracts are the conspicuous part of the so-called 

 Edelweiss "flower." 



But to return to the woolly coat : What is the 

 purpose of this adaptation ? Why is it present in this 

 plant and not in others ? 



It must be remembered that the Edelweiss usually 

 flourishes in very dry situations, where there is com- 

 paratively little moisture in the soil. In this respect 

 it is like a plant growing in a desert. Consequently 

 it has to husband such water as it can absorb from 

 the soil by means of its roots with the greatest care. 

 Were it to transpire rapidly (see p. 12) i.e., give 

 off water-vapour the supply would run short, and 

 the stream of water passing from the soil to the 

 atmosphere, by means of the root, stem, and 

 leaves, would soon cease. Thus some contrivance 

 must be arrived at, which will prevent an undue loss 

 of water from the surface of the plant by evapora- 

 tion. The hairy coat is this contrivance, and therein 

 lies the great point of botanical interest presented by 

 this plant. The fact that, not only the leaves, but 

 the head- stalk, and even' the heads of flowers, all of 



