78 THE AMERICAN BOTANIST 



the snow more readily and thaw and warm the soil to a 

 greater depth. The thin air of these high altitudes, lacking 

 in moisture and haze of any sort, favors reflection rather 

 than absorption of the sun's heat so that the ground above 

 timberline does not thaw, even in summer, to a depth suf- 

 ficient to liberate moisture enough to support tree life. 



The soil is made up of the detritus from the weathering 

 of the ruddy pinnacles, the sheer faces of the cliffs and the 

 aged, isolated boulders. The frosts and storms of innum- 

 erable blustery winters have liberated these granitic par- 

 ticles and whirled them over and over and down, ever 

 grinding them finer. To this rock-waste have been added 

 through countless centuries the products of vegetable decay 

 and the droppings of birds and animals. Thus, there has 

 slowly accumulated a thick blanket of loose, gravelly soil 

 that covers all but the most resistant ridges, the highest, 

 .most irregular rock fields and the deepest, sheerest abysses. 

 It smooths many of the lesser spurs into rounded, undulat- 

 ing forms and softens the skylines into gentler angles save 

 where the hardest "rocky ribs" jut through it. Of consider- 

 ate depth for some distance above the treeline, it supports. 

 a dense growth of grasses and sedges, some shrubby wil- 

 lows and other shrubs and a great variety and brilliant 

 profusion of flowering herbs. It thins out towards the 

 summits and passes into isolated pockets among the rocky 

 outcroppings. The grasses and shrubs disappear and only 

 a few most enduring plants are to be found in the crannies 

 of the highest peaks. 



The great majority, probably all, of these high Alpine forms 

 are perennials. They bear seeds and increase in numbers by 

 this means, but they rely upon enduring roots of various forms 

 to perpetuate the individuals. The large number of different 

 plants is a revelation to those who have been taught to regard 

 the mountain peaks as barren wastes of rock. At least 250 



