SHADE TREES. 135 



balm of Gilead (P. candicans) have been planted occasionally on streets 

 and near dwellings for many years. The former, which is characterized 

 by its silverj' leaves, grows to a large, widespreading tree. 



Black Locust {Robinia pseudacacia) . — • The black locust is one of our 

 most rapidly growing trees, and while it is spontaneous here it is native 

 farther south than New England. It adapts itself to severe conditions, 

 and withstands obnoxious atmospheric gases better than any other tree, 

 but it is so attacked by borers at times as to render its use as a street tree 

 of little account. It is a valuable honey tree, and may be employed as a 

 hedgerow or screen near dwellings, and near smelters and large man- 

 ufacturing plants where noxious gases prevail. 



Honey Locust {Gleditschia triacanthos) is a tree reaching large dimen- 

 sions and provided with stout thorns. It is sometimes used in planting. 



Chestnut {Castanea dentata) frequently grows profusely along road- 

 sides and at times on lawns. It is not adapted to street planting on 

 account of the litter accompanying fruiting, and its rapid destruction 

 from the blight at present renders this species useless for any purpose, 



Hackberry (Celtis occidentalis) , which is closely related to our elm, 

 is found sparingly in some of our river valleys, and occasionally met 

 with on streets side by side with the elm. During recent years some have 

 advised planting this tree instead of the elm, as it is said to be less sus- 

 ceptible to insects, particularly the elm-leaf beetle. It is a much inferior 

 tree, however, to the elm. 



Hardy Catalpa (Catalpa speciosa) is more at home in the west, al- 

 though used here as an ornamental tree. With us it does not sustain its 

 western reputation for growth, and according to our observations it has 

 little or no value as a street tree in most northern sections. 



Some of the willows are employed effectively for planting near marshes 

 and low, swampy grounds. They afford protection to roadsides and are 

 valuable as screens to unsightly places. The laurel-leaved or bay willow 

 (Salix pentandra), which attains a height of 20 or 25 feet, is used on 

 country roadsides and sometimes on lawns. It has dark green, glossy 

 foliage. It is adapted to hedges and thrives well near the seashore. The 

 weeping willow (Salix babylonica) and a few other forms are planted for 

 ornamentation and shade-producing effects. 



Fine individual specimens of the black walnut {Juglans nigra), a tree 

 sparingly native in New England, may be seen on lawns, but according 

 to our observations on the results of planting this species on roadsides it 

 appears to be a failure as a shade tree. 



Box elder (Negundo aceroides) is occasionally grown near dwellings, but 

 is not a satisfactory street tree under New England conditions. 



The various conifers may be used under suitable conditions, such as 

 on country roadsides, and some use is made of them for this purpose. 

 The white pine and Norway spruce are sometimes planted along road- 

 sides, and are especially valuable as wind breaks. The European larch, 

 Scotch and Austrian pines, as well as our superior red pine, may be em- 



