68 
NEIGHBORING IMPROVEMENTS. 
Street Trees. 
The subject of street trees comes properly under the head of 
neighboring improvements. It might be inferred, from the modes 
of planting recommended in the preceding pages, that a variety of 
trees will be recommended for one street in preference to a single 
sort. On the contrary, the effect is much better, on a straight 
street or road, to have an avenue composed of a single species of 
tree only. To attempt the varieties of park scenery on an avenue 
is as much out of place as to compose a park of straight rows of 
trees. There ought to be but one variety of street tree on the 
same block, at least, and the longer the continuity is kept up the 
nobler will be the effect. Street trees are usually planted quite too 
close together. For wide avenues (where alone such great spread¬ 
ing trees as the elm, sycamore, silver maple, and silver poplar 
should be planted), from thirty to fifty feet apart is near enough, 
and thirty feet is the least distance that any street trees should be 
planted from each other. The finest deciduous trees are those 
already most commonly planted—elms, maples, and horse-chest¬ 
nuts. The white pine is a noble street tree, very little used. It 
deserves to be; but as it must be planted of smaller size than the 
deciduous trees, in order to do well, and therefore requires box pro¬ 
tection during a greater number of years, it should only be planted 
where such protection is sure to be given. No trees should be 
planted, in streets, which do not come early into leaf, or which have 
disagreeable blossoms, or which bear nuts or eatable fruit, or the 
leaves of which are subject to worms, or do not drop promptly and 
dry after the first severe autumn frosts. The different varieties of 
the maple, the horse-chestnut, the weeping elm, and the English 
and Scotch elms, all unite to a great extent the best qualities for 
street trees. The linden is peculiarly subject to worms, and should 
not, therefore, be planted in streets. The elm, near the sea-coast, 
is also infested by a species of worm, which does not, however, 
seem to be very annoying in the interior. The tulip tree, or white 
wood, is rather difficult to transplant, and not adapted to any but a 
rich warm soil; but, once established in such a soil, it makes an 
elegant street tree. The oaks grow too slowly to be popular, and 
