14 



WILD FLOWERS AND TREES OF COLORADO 



intense light of the noon-day sun which shines through so little atmosphere 

 that it is very bright indeed. As a result of these various unfavorable 

 conditions the mountain tops are able to support only a very sparse 

 growth of plants. 



Dryness of soil, intense light, high winds, low temperatures and short 

 summers are all unfavorable to tall growth of plants. But the author 



J5dlif< f*A'& f ^"Ma£. 



Fig. 14. — A Broad Valley in the Rock Ridge Country 

 Foldings are seen in the geological strata across the valley. In the foreground are 

 cottonwoods and various deciduous trees and shrubs. 



believes that these are not really the cause of the dwarf habit of alpine 

 plants. Alpine plants are plants which have naturally a low, matted 

 form and are therefore able to grow under the severe conditions of the 

 alpine climate. Any other kind would be killed. There are many low, 

 matted plants which grow on the dry plains, too, and on the bare rock 

 ridges of northern Colorado. 



It is perfectly natural that there should be a difference in the plants 



