522 CULTIVATION OF ALPINE FLOWERS. 
usually devoid of soil; but we must not conclude therefrom 
that the choice jewellery of plant-life scattered over the ribs 
of the mountain, or the interstices of the crag, live upon 
little more than the mountain air and the melting snow! 
Where will you find such a depth of well-ground stony soil, 
and withal such perfect drainage, as on the ridges of débris 
flanking some great glacier, stained all over with tufts of 
crimson saxifrage? Can you gauge the depth of that narrow 
chink, from which peep tufts of the diminutive and beautiful 
Androsace helvetica? No; it has gathered the crumbling 
grit and scanty soil for ages and ages; and the roots enter 
so far that nothing the tourist carries with him can bring out 
enough of them to enable the plant to live elsewhere." Al- 
pine plants are peculiarly exposed to sudden alternations of 
heat and cold, of moisture and dryness. The cold, almost 
frosty, night will be followed, in July and August, by an 
unclouded day, when the rays of the sun beat on the un- 
sheltered surface of the rock with an intensity that would 
scorch up many an English meadow plant. Only a very 
small proportion of alpine plants are annuals; and they are 
frequently provided with a storehouse of nourishment in the 
form of rosettes or tufts of thick succulent leaves; but their 
chief water supply is through their roots; and thus we find 
that while our garden annuals have fibrous roots of insignifi- 
cant dimensions, and even our forest trees will seldom strike 
their roots to a greater depth than the height of their foliage, 
the roots of alpine plants, scarcely an inch in height, will be 
found to penetrate the chinks between the rocks full of rich 
earth, to the depth of sometimes more than a yard, or forty 
times the height that they venture into the air. The neglect 
of this most essential condition for the growth of alpine plants 
is of itself amply sufficient to account for the failure which 
has generally accompanied the attempts to introduce these 
lovely flowers to our rockeries. A good depth of soil is in- 
deed more indispensable to these plants than the presence of 
rock and’ stone. They no doubt prefer to expand their 
