136 MASS. EXPERIMENT STATION BULLETIN 170. 



ployed advantageously for the same purpose. The shade produced by 

 roadside planting is beneficial to a roadbed, as it prevents the rapid 

 evaporation of water from the surface, and has a similar effect in this 

 respect to some chemical road dressings in controlling dust. Moreover, 

 a roadbed under such conditions retains its surface better than one con- 

 stantly exposed to the sun, and there is less trouble from drifting snow. 

 Since new plant material is being constantly introduced into the United 

 States from foreign countries there is a likelihood of some new and desir- 

 able species of shade trees 

 becoming available in the 

 future. 



The large and unrivaled 

 collection of trees to be 

 seen in the Arnold Arbo- 

 retiun, Jamaica Plain, 

 Mass., furnishes good ex- 

 amples for consideration. 

 According to the most 

 experienced planters the 

 trees best suited for street 

 purposes in New England 

 are as follows: elm, rock, 

 white, red and Norway 

 maples, red, scarlet and 

 inn oaks, bassivood, tulip 

 tree. Ginkgo, encumber 

 tree, hackberry, English 

 dm, horse-chestnut, syca- 

 more and ivhite ash. 



For wide avenues large 

 species such as the elm, 

 rock and ivhite maples, 

 tulip tree, sycamore, etc., 

 are recommended; and for narrow streets the pin oak, Norway maple, 

 sweet gum, catalpa. Ginkgo and horse-chestmd. For severe conditions 

 the English elm, horse-chestnut, linden and Ailanthus are considered 

 the most desirable species. No fixed rule, however, can be laid down 

 as regards the use of the different species of trees for wide, medium 

 or narrow streets, as different effects in planting are often sought. 

 Indeed, one of the most serious defects in planting of all kinds is the lack 

 of originality. Imitation in methods, the constant use of certain species 

 and varieties, and the extreme conventional effects often pi'oduced be- 

 come wearisome, while the marked diversity of Nature's planting, always 

 resourceful in producing harmonious effects, never becomes tiresome. In 

 general, however, the large type of shade tree, like the elm, maple and 

 others, should be used on wide streets, and those having a more pyram- 



FiG. 8. — Street with ideal tree tielt. (See Fig. 13.) 



