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STREET TREES. 29 
overcome. The tree is practically disease and insect free, with the 
exception of a liability to infestation by a leaf aphis* which pro- 
duces yellow spots on the leaves and causes them to drop prema- 
turely; also, the honeydew which they produce is so abundant at 
times as to cover the leaves and wet the sidewalk beneath the 
tree, the leaves under certain weather conditions becoming blackened 
with dust accumulating and a fungus growing in the secretion, 
thereby giving the tree an unsightly appearance. This aphis, how- 
ever, is not always present and does not seriously injure the tree. 
The Norway maple comes into leaf later than most of the other 
maples, but holds its leaves later in the fall. They usually assume 
a bright yellow hue before they drop. The leaves are preceded 
by an abundance of yellow-green blossoms. On account of its dense 
shade and masses of fine fibrous roots it is difficult to grow grass 
under this tree. Its good shape and attractive dark-green foliage 
make it popular for street planting in spite of its dense, low head. 
It will succeed in regions 1, 2, 3, 4, 9, 10, 11, and 12. 
The Oregon maple? is the large-leaved maple of the northern 
Pacific slope. It forms a large round head, and with its unusually 
large dark-green leaves makes a very attractive street tree that 
succeeds well in regions 1, 2, 3, and 4. It is valuable and worthy 
of more extended cultivation on the Pacific coast. 
The red maple,? scarlet maple, or swamp maple is one of the 
most widely distributed of American trees. It is found from Canada 
to the Gulf of Mexico and west to the Rocky Mountains. Its leaves 
are the smallest of any of the eastern native maples, but it grows 
large and the trees are usually of rather upright outline. It is 
better adapted to suburban conditions than to city streets and is 
one of the few trees that succeed well near the ocean. It has bright- 
red blossoms before the leaves appear. The young leaves and fruits 
are also red. The mature leaves begin to color early, some branches 
coloring as early as the middle of July, assuming brilliant reds and 
yellows and staying on later than those of the sugar maple. It is 
a handsome tree that is not as much used as it deserves to be in 
necrons) (59 10, ial, and 13: 
The silver maple,* also called the soft maple, white maple, and 
swamp maple, is probably more used for street planting through 
the whole United States than any other tree, and with one excep- 
tion it is the least desirable. Jt is usually planted because it is a 
quick-growing tree, but it is not more rapid in growth than several 
other much better trees. There are three serious objections to its 
use as a Street tree. The first is its brittle wood, which at an early 
1 Periphyllus lyropictus Kess. (Data furnished 3 Acer rubrum L. 
by the Bureau of Entomology.) 4 Acer saccharinum L. 
2 Acer macrophyllum Pursh. 
