[Illustration: FIG. 50.--Gray or White Birch Trees.]

Leaf: The stem of the leaf completely covers the bud. This is a
characteristic peculiar to sycamores.

Form and size: A large tree with massive trunk and branches and a broad
head.

Range: Eastern and southern United States.

Soil and location: Prefers a deep rich soil, but will adapt itself even
to the poor soil of the city street.

Enemies: The sycamore is frequently attacked by a fungus (_Gloeosporium
nervisequum_), which curls up the young leaves and kills the tips of
the branches. Late frosts also often injure its young twigs. The
Oriental sycamore, which is the European species, is more hardy in
these respects than the native one and is therefore often chosen as
a substitute.

Value for planting: The Occidental sycamore is now planted very little,
but the Oriental sycamore is used quite extensively in its place,
especially as a shade tree. The Oriental sycamore is superior to the
native species in many ways. It is more shapely, faster growing, and
hardier than the native one. Both sycamores will bear transplanting
and pruning well.

[Illustration: FIG. 51.--Bark of the Black or Sweet Birch.]

Commercial value: The wood of the sycamore is coarse-grained and hard to