8 SHADE-TREES IN TOWNS AND CITIES 



Straightness and Symmetry. A tree planted on a lawn 

 may have the branches drooping, the stem crooked, and the 

 shape unsymmetrical ; but in this case these oddities in its 

 habits are in themselves elements of beauty. A tree, in 

 order to be adapted for street use, however, must have a 

 straight stem, a rounded, well-filled head and be symmetri- 

 cal in growth. Its shape is to be, in a certain sense, formal ; 

 but, at the same time, it should not be produced entirely by 

 artificial pruning. The tree must lend itself to the require- 

 ments of the public use of the highway and preserve, as far 

 as possible, its natural habit of growth. 



Immunity from Insect Attack. In the selection of shade- 

 trees, their relative immunity from insect attack is a point 

 to be considered. While there are few trees that are abso- 

 lutely free from pests, some trees enjoy greater immunity 

 than others, and, if otherwise desirable, such trees should 

 be preferred. 



Abundance of Shade. Trees that retain their foliage in 

 good condition throughout the summer and show changes of 

 color in autumn are most desirable. Trees that naturally 

 grow an open, scraggly head are not adequate for shade 

 production, and, again, a dense shade during the summer 

 is objectionable because it cuts off sunlight, prevents the 

 growth of grass under the trees, and retards the drying of 

 the highway after rain. 



Cleanliness. Cleanliness in habits of growth is an es- 

 sential characteristic of good street-trees. The falling of 

 leaves, twigs, bark, flowers, and fruits keep the sidewalks 

 in a state of untidiness, while slippery fruits are dangerous 

 as well as unsightly. Tempting flowers or fruits cause peo- 

 ple to injure the trees, and it is manifestly out of place to 

 attempt to grow trees for their fruit on the street. 



