work; used occasionally for inside finishing in buildings.

Other names: _Buttonball_, _buttonwood_.

Comparisons: The _Oriental sycamore_ (_Platanus orientalis_) an
introduced species, is apt to be confused with the Occidental
sycamore, but may be told from the latter by the number of seed
balls suspended from the tree. In the case of the Oriental species,
the seed balls hang in _pairs_ or (rarely) three or four together.
In the Occidental, the seed balls are generally _solitary_ and very
rarely in pairs.


GRAY OR WHITE BIRCH (_Betula populifolia_)

Distinguishing characters: The *dull-white color of the bark* on the
trunk and the _dark triangular patches below the insertion of the
branches_ distinguish this tree; see Fig. 50. The bark of the young
trunks and branches is reddish-brown in color and glossy. The bark
adheres closely to the trunk of the tree and does not peel in loose,
shaggy strips, as in the case of the yellow or golden birch. It is
marked by small raised horizontal lines which are the lenticels or
breathing pores. These lenticels are characteristic of all birch and
cherry trees. In addition to the distinction in the color of the
bark, an important character which distinguishes the gray birch from
all other species of birch, is found in the *terminal twigs*, which
are *rough* to the touch.

Form and size: A small tree. Frequently grows in clumps.