Street Trees. 



327 



establish transplanted specimens, yet its successful application under 

 different conditions requires years of experience. Trees that have been 

 root-starved or suffocated with gas are often preserved by this practice. 



(3). To open up the head of the tree. It frequently happens that trees 

 become crowded and cannot attain their normal and best development 

 without being subjected to a thinning process. As a rule, street trees 

 should be adapted to specimen planting, and the full development of 

 such trees cannot be expected under crowded conditions. The interior 

 of the trees should have free light and air. Competition for light 

 among the branches can be reduced greatly by removing those 

 w^hich in the course of time must be crowded out and suffocated. 

 Trees that are suft'ering from overcrowding of branches should be 

 intelligently thinned out, in order that the branches that remain may 

 develop a greater leaf surface. 



(4). To adapt the species to street purposes as shade trees. It is seldom 

 necessar}' to prune certain species of trees to adapt them to street plant- 

 ings. Trees should not be chosen that must be pruned continually 

 in order to make them desirable. Occasionally one may find an ave- 

 nue of trees that are not adapted to their situation. In such in- 

 stances, rather than cut the trees down, the avenue may be made 

 attractive by judicious pruning, as by removing or shortening in some 

 of the branches, or removing such lower branches as may interfere 

 with traffic. Occasional^, because of the breaking of a branch during 

 a storm, it becomes necessary to develop a branch to fill the gap and 

 restore the symmetry of the tree. This is done by selecting a branch 

 and cutting it back to a branchlet that points in the direction of the 

 gap, and then encouraging the development of this branchlet. 



(5). To control the production of flowers. Street trees are not valuable 

 primarily because of their flowering habits, and frequently it happens 

 that trees are objectionable because of this feature, since the presence 

 of showy flowers subjects them to much damage from marauding persons. 

 This is especially true of the tulip tree, flowering dog^vood, horse- 

 chestnut and magnoHa. Such trees as flowering dog^\'ood and some of 

 the magnolias, w^hich flower early in the spring and on wood formed 

 ■the year before, require pruning after the trees are done flowering each 

 year. Pruning previous to the time of flowering removes a number 

 of flower-buds already formed, whereas pruning immediately after 

 flowering serves to encourage the growth of new branchlets on which 

 will be formed more flowxr buds for the succeeding year. Pruning to 

 control the production of flowers is practiced more extensively with 

 shrubs than with trees. 



