REPORT ON TREE-PRUNING. 35 



limited. A leading shoot, therefore, in the plane tree is not a 

 terminal one in the sense in which it is so in a fir, for instance, 

 but is always an extension of a lateral bud — and that not close 

 to the top — of a parent shoot, the upper part of which dies back 

 to, or near to, the point of origin of the lateral bud. In con- 

 sequence of this method of development, there may be several 

 shoots on different branches competing for the position of leader, 

 and the one that is successful in any year is not necessarily the 

 parent of that one which is the dominant leader in the succeeding 

 year. And, indeed, in nature there is often no distinct leader. 

 There follows from this that when a single main stem is formed, 

 it does not come from the continued growth of a single axis 

 elongating at its summit year after year, but is the product of 

 the combination, in more or less vertical line, of the bases of 

 branches arising in succession one from the other. What 

 appears to be a simple axis tapering from base to summit is really 

 constructed out of annually formed segments, each the base 

 of a lateral branch, of which the upper part has commonly died 

 in part or in whole. The forking of the stem results from the 

 development of two such systems of segments. The significance 

 of this is evident. The tree in nature is always checking its 

 leader. It is adding to the length of its main stem, not by 

 uniform summit growth of one shoot, but in a zigzag manner 

 through the bases of successive shoots, the top parts of which 

 are arrested and die. The length of segment added yearly 

 varies with the position on the shoot of the bud which develops 

 into the temporary leader. 



That is nature's process. The procedure in the Mall follows 

 it, but on systematic lines : — 



(a) Selection, not the chance outcome of a struggle betwixt 

 competing shoots, determines the position of the 

 shoot that is to be leader. 

 {d) Selection determines also, in relation to the general 

 growth in each successive year, the length of the 

 base of the leader that is to be added as a 

 segment to the summit increase of the main 

 stem. 

 (c) And then for the method of slow decay by which nature 

 rids the tree of the upper part of the quondam leader, 

 is substituted the prompt definite operation of the 

 pruning-knife. 



