446 PLANTS AND THEIR RELATION TO MAN 



Taking care of trees. Many people admire trees and are 

 glad to have them in gardens or on pavements, but few under- 

 stand the needs of trees and are willing to give time to them. 

 A tree cannot be planted and left to shift entirely for itself; 

 it must be pruned, must be kept free from caterpillars, must be 

 protected against horses (Fig. 311) by 

 metal guards, and must be watered oc- 

 casionally during a long dry summer. 

 The owner must not cement close around 

 the tree trunk and shut off air and water 

 from the roots, but must leave a free 

 space around the base of the tree so that 

 rain and water can soak to the roots, and 

 fertilizer can be spread on the soil. A 

 fine, healthy tree cannot be had with- 

 out care from the owner, but the actual 

 daily care is small, and is far less than 

 the pleasure and benefit yielded by the 

 tree. 



The importance to a community of 

 growing plants and trees is now so keenly 

 felt that many cities have permanent 

 Park and Tree Commissions whose 

 duty it is to provide parks for the 

 citizens, to plant suitable trees on the sidewalks, to prune the 

 trees regularly, and to care for them generally (Fig. 312). The 

 expense of this work is paid by a small tax on the citizens, 

 and so far the plan has been successful. The men employed 

 by the commissions are experts who understand what to 

 plant, how to plant, and when to plant. They also understand 

 pruning and spraying for insects, and thus they keep the trees 

 in excellent condition without much direct aid from the 

 household. If, however, such a commission does not exist 



FIG. 311. A tree injured 

 by horses. 



