THE WILLOW. 315 



comes the Herbaceous Willow, Salix herlacea. The 

 ordinary height of this diminutive tree is about four 

 inches. It is a native of many parts of Europe, and of 

 l^orth .America, and in Great Britain is the last plant 

 furnished with a woody stem which we meet in ascending 

 the mountains. 1 "In Switzerland," De Candolle observes, 

 " some species of Willow spread over the uneven surface 

 of the soil ; and as their branches are often covered with 

 the earth which the heavy rains wash over them, they 

 present the singular phenomenon of trees which are more 

 or less subterranean. The extremities of these branches 

 form sometimes a kind of turf, and the astonished traveller 

 finds himself, as we may say, walking on the top of a tree. 



HERBACEOUS WILLOW. 



Salix kerbacea is the species that most frequently presents 

 this remarkable appearance, because it generally grows on 

 steep slopes of loose soil." The leaves are employed in 

 Iceland in the tanning of leather. 



The Willow is liable to the attacks of a gall-fly, which, 

 in the summer, lays its eggs in the young twigs. The 

 effect is, that the juices of the tree, diverted from their 

 natural use, harden into an irregular mass, which, when 

 the young grubs are hatched, serves them both for food 

 and dwelling. While the trees are in leaf, these galls are 



1 See "Botanical Rambles," page 123, 16mo edition. 



p2 



