THE CARE OF STREET-TREES 111 



free public use of the street. Besides, the tree must have 

 a well-developed, compact head, as nearly as possible of 

 oval outline. Many of the requisites of the good tree will 

 be obtained by selecting the proper species for planting. 

 To produce symmetry, good outline, and branching at a 

 fixed height from the ground are the functions of training 

 and pruning. 



Fixing Height of Branching. — The training of the tree 

 should begin soon after planting. The fixing of the branch- 

 ing at a certain height above the ground must be done grad- 

 ually, however. It is desirable that a tree should grow in 

 diameter as well as in height in order to support the top 

 without bending. Low branching will cause a more rapid 

 growth in thickness. The lower layers of branches should 

 be removed at intervals of a year or more until the proper 

 height of clean stem, ten or twelve feet, is reached. 



Forming the Crown. — The training of the crown consists 

 in shaping it for symmetry by the suppression of some 

 branches and the encouragement of the growth of others. 

 If possible, trees should be left with single leaders. Two or 

 three main stems produce crotches which are likely to split 

 in later years. When there is a tendency to the formation 

 of two or more main stems, the central stem should be left 

 and the others entirely removed, or so shortened that the 

 entire vigor of growth will be thrown into the central stem. 

 In the case of young oaks and other species of trees, of 

 which the wood is very flexible, the leaders have a tendency 

 to bend over, and the tops in time become drooping. In 

 such cases the leaders should be tied to bamboo poles of 

 about an inch or an inch and a quarter in diameter. Raffia 

 is one of the best materials to use in tying trees to bamboo 

 poles. When a tree loses its leader, it can be made to re- 



