INTRODUCTION. 



Alpine plants fringe the vast fields of snow and ice of the 

 high hills, and at great elevations have often scarcely time 

 to flower and ripen a few seeds before they are again im- 

 bedded ; while sometimes, if the previous year's snow has 

 been very heavy, and the present year's sun is weak, nunibers 

 of them may remain beneath the surface for more than a 

 year. Enormous areas of ground, inhabited by alpine plants, 

 are every year covered by a deep -bed of snow. Where the 

 tall tree or shrub cannot exist from the intense cold, a deep 

 soft mass of downy snow settles upon these minute plants, 

 like a great cloud-borne quilt, under which 'they rest un- 

 tortured by the alternation of frost and biting wind with 

 moist, balmy, and spring-like days. 



But let it not for a moment be supposed that these 

 conditions are indispensable for their growth I The reason 

 that they predominate in these very elevated regions is 

 that no taller vegetation can exist there. Were these 

 places inhabited by trees and shrubs, we should yet find 

 alpine plants among them, but much fewer than in the 

 rocky fields where they reign supreme. Thus many plants 

 found on the high Alps, and popularly considered to grow 

 only within sight of or among fields of snow, are met 

 with in open rocky or bare places at much lower eleva- 

 tions. Gentiana verna, for example, is one of the loveliest 

 gems in the Flora of the Alps, often flowering late in the 

 summer when the snow thaws on a high mountain ; yet it 

 is also found on comparatively low hills, and occurs in 

 .Ireland and England. Numbers of other subjects could 

 be mentioned of which the same is true. In the fierce 

 struggle for existence upon the plains and low tree-clad 

 hills, the more minute species are often overrun by trees, 

 trailers, bushes, and vigorous herbs, but where in northern 



