size and produces an open spreading
head. Its leaves, twelve to eighteen inches long, are larger than
those of the other magnolia trees. The tree is sometimes called
_elkwood_.

BLACK LOCUST (_Robinia pseudacacia_)

Distinguishing characters: The *bark* of the trunk is _rough_ and
_deeply ridged_, as shown in Fig. 81. The *buds* are _hardly
noticeable_; the twigs sometimes bear small spines on one side. The
leaves are large, compound, and fern-like. The individual leaflets
are small and delicate.

Form and size: The locust is a medium-sized tree developing a slender
straight trunk when grown alongside of others; see Fig. 82.

Range: Canada and United States.

Soil and location: The locust will grow on almost any soil except a wet,
heavy one. It requires plenty of light.

Enemies: The _locust borer_ has done serious damage to this tree. The
grubs of this insect burrow in the sapwood and kill the tree or make
it unfit for commercial use. The _locust miner_ is a beetle which is
now annually defoliating trees of this species in large numbers.

Value for planting: It has little value for ornamental planting.

Commercial value: Though short-lived, the locust grows very rapidly. It
is extremely durable in contact with the soil and possesses great
strength. It is therefore extensively grown for fence-posts and
railroad ties. Locust posts will last from fifteen to twenty years.
The wood is valuable for fuel.

[Illustration: FIG. 82.--Black Locust Trees.]

Other characters: The _flowers_ are showy pea-shaped panicles appearing
in May and June. The _fruit_ is a small pod.

Other common names: _Yellow locust_; _common locust_; _locust_.

Comparisons: The _honey locust_ (_Gleditsia triacanthos_) can be told
from the black locust by the differences in their bark. In the honey
locust the bark is not ridged, has a sort of dark iron-gray color
and is often covered with clusters of stout, sharp-pointed thorns as
in Fig. 83. The fruit is a large pod often remaining on the tree
through the winter. This tree has an ornamental, but no commercial
value.

[Illustration: FIG. 83.--Bark of the Honey Locust.]

HARDY CATALPA (_Catalpa speciosa_)

Distinguishing characters: The tree may be told by its *fruit*, which
hang in long slender pods all winter. The leaf-scars appear on the
stem in whorls of three and rarely opposite ea