STEMS AND BRANCHES AND THEIR USES 219 



an excellent means of replacing lost parts and sometimes of 

 multiplying its numbers under unfavorable conditions. The 

 branch that grows from an adventive bud is an adventive 

 branch. 'New branches often appear upon the trunk of a tree 

 about the place from which a branch has been removed. 

 Often the new branches are adventive branches. But this is 

 not always the case ; for it has been found that the axillary 

 buds of many forest trees can remain alive under the bark 

 for a long time, in some cases even for years, without develop- 

 ing. Some of the new branches, therefore, that grow from 

 the neighborhood of wounds, may come from resting buds 

 that were originally formed in the axils of leaves. 



When a branch is cut back, also, it often sends out several 

 or many side branches, some of which may come from adven- 

 tive buds and some from resting axillary buds. This tend- 

 ency of trees when cut back to form new side branches is taken 

 advantage of in the pruning of shade trees to secure a sym- 

 metrical top, in the production of dwarf trees and trees of 

 various unusual forms, and in the trimming of ornamental 

 shrubs and hedges. If the top of a willow is cut off, many 

 new branches appear just below the cut surface and grow 

 into a new compact head. What is called coppice growth 

 results from the cutting off of the trunks of good-sized trees 

 at the surface of the ground. The numerous adventive shoots 

 that start are allowed to grow to the desired height and are 

 then cut, to be used in basket-making, for small firewood, 

 and for many other purposes, varying with the kind of tree 

 from which they come. The removal of the first lot of shoots 

 is followed by the growth of a new lot, and so the same root 

 system serves for the rapid production of many crops. Vari- 

 ous kinds of injuries those caused, for example, by bruises, 

 by biting and boring insects, and by the growth of the para- 

 sitic fungi that form "witches' brooms " may furnish the 

 stimulus for the development of adventive buds and 

 branches. 



