THE WHITE DRYAS 107 



short and buried in the soil. Just above the ground 

 a very large number of long prostrate branches spread 

 over a considerable area, packed closely together. 

 The branches bear numerous little tufts of leaves, and 

 thus a gi'een carpet of close texture, often occupying 

 many square feet in extent, is woven over the soil. 



The stems of many of these carpet plants reach a 

 great age. In the case of Dryas, as many as a 

 hundred years have been recorded on the evidence of 

 the rings of growth of the woody tissues of the stem, 

 as seen in transverse section. Thus these lowly 

 plants are as permanent as many of the trees of a 

 forest. 



This type of habit has many advantages. It 

 ensures space for the production of a very large 

 number of flowers and consequently seeds. This we 

 have seen to be a prime necessity for many Alpine 

 plants. The close, compact nature of the carpet is 

 very successful in preventing the intrusion of other 

 plants on the same ground. Nothing can live beneath 

 it. In the Alps the struggle for room leads to a 

 daily war among plants. Not only does a carpet 

 plant hold its ground successfully, but by the increase 

 in the length of the branches it can increase its 

 holding and oust out other plants which happen to be 

 situated near the margin of the carpet. In winter- 

 time also, when all the world is wrapped in snow, 

 this particular habit is no doubt extremely well 

 adapted to withstand the weight of the overlying 

 snow, and thus to ensure the plant against injury. 



