THE AMERICAN BOTANIST 



79 



species of conspicuous flowering plants and 75 or 80 more of 

 grasses and sedges occur there. Some few are peculiar to the 

 mountains of certain localities but more than half of them are 

 common to all the high mountains of Western North America. 



Harebells nodding among the ripened grasses. 



Many of them grow in the Arctic lands and islands as well, 

 and some are known to be circumpolar. 



The growth and distribution of Alpine plants depends 

 largely upon the amount of nv isture at their disp sal. Growth 

 starts as soon as the water from the melting snow reaches 

 their roots. Plants like the Penny-cress ( Thlaspi coloradcnsc) 

 and the mountain forget-me-not (Eritrichium argenteum) 

 often bloom while the snow actually covers them and are always 



