on the other.

Form and size: A small or medium-sized tree with a single stem and broad
conical crown.

Range: United States and Canada.

Soil and location: Grows naturally in fertile soils, but will adapt
itself to almost sterile soils as well.

Enemies: The hackberry is usually free from disease, though often its
leaves are covered with insect galls.

Value for planting: It is extensively planted as a shade tree in the
Middle West, and is frequently seen as an ornamental tree in the
East.

Commercial value: It has little economic value except for fuel.

Other characters: The _fruit_ is berry-like, with a hard pit. The fleshy
outer part is sweet.

Other common names: _Nettle tree_; _sugarberry_.

GROUP VIII. THE OAKS AND CHESTNUT

How to tell them from other trees: The oaks are rather difficult to
identify and, in studying them it will often be necessary to look
for more than one distinguishing character. The oaks differ from
other trees in bearing _acorns_. Their _leaves_ have many lobes and
their upper lateral _buds_ cluster at the top of the twigs. The
general contour of each oak presents a characteristic branching and
sturdiness uncommon in other trees.

The chestnut differs from other trees in bearing _burs_ and its
_bark_ is also distinctly characteristic.

How to tell them from each other: There are two groups of oaks, the
_white oak_ and the _black oak_. The white oaks mature their acorns
in one year and, therefore, only acorns of the same year can be
found on trees of this group. The black oaks take two years in which
to mature their acorns and, therefore, young acorns of the present
year and mature acorns of the previous year may be found on the same
tree at one time. The _leaves_ of the white oaks have rounded
margins and rounded lobes as in Fig. 57, while those of the black
oaks have pointed margins and sharp pointed lobes as shown in Figs.
60, 62 and 64. The _bark_ of the white oaks is light colored and
breaks up in loose flakes as in Fig. 58, while that of the black
oaks is darker and deeply ridged or tight as in Figs. 59 and 61. The
white oak is the type of the white oak group and the black, red and
pin oaks are types of the other. For the characterization of the
individual species, the reader is referred to the following pages.

[Illustration: FIG. 57.--Leaf and Fruit of Wh