A Street Tree System for Neiv York City 51 



way where the trees are growing in a few feet of soil above 

 the subway roof. This tree has few enemies, and can easily 

 be kept in fine foliage. It is adapted for nse as a normal 

 sized tree in deep soil as well as for pruning to a limited 

 size where the soil is shallow. The Pin Oak is no more 

 hardy than the Red Oak, but on account of its slower 

 growth is more adaptable to adverse street conditions. 



G. Popultjs deltoides (var. C ' aroliniensis) . (The Caro- 

 lina Poplar) . 



The Carolina Poplar is generally held in bad repute as a 

 street tree because of the tendency of its roots to clog sewers 

 and water pipes and because the brittle nature of its wood 

 makes it liable to injury in storms. However, if the tree 

 is kept pruned to a small size and formal shape, both these 

 objections are largely overcome, and its luxuriant green 

 foliage, even under the most adverse conditions, make it 

 very valuable for certain locations. It is well adapted for 

 use when pruned in this manner on congested business 

 streets grown in a restricted tree pit beneath a grating. 

 Being a rapid grower and easily moved when of fair size it 

 would be possible with this tree to maintain uniform tree 

 lines of formally pruned trees on streets where few other 

 trees could be made to succeed.* 



7. Ailanthus glandulosa (The Tree of Heaven). 



The Ailanthus is even more hardy than the Plane, the 

 Gringko or the Poplar and requires a minimum of soil and 

 water to succeed. This tree will grow luxuriantly where 

 no other tree could exist, and this is its chief value in any 

 list of street trees. In appearance it is fair, the foliage be- 

 ing rather coarse and tropical in effect, but always of a 

 luxuriant green. The tree tends to grow straggly, and has a 

 rather unsightly appearance in the winter. The Ailanthus 



* The Shade Tree Commission of Newark has used the Poplar treated 

 in this way with considerable success. There exists on lower Fifth 

 avenue several trees thus pruned which are among the most effective 

 and successful street trees to be found in New York. 



