have a label fastened
to them with a piece of wire. Unless this wire is removed or is
carefully watched and enlarged from time to time it will cut into the
bark as the stem grows and interfere with its work and often kill the
top of the tree or injure a main branch.

These are a few ways in which the work of the stem is sometimes
checked and the plant injured thereby.

CHAPTER XV

FLOWERS

In our study of the parts of plants the flower and fruit have been
given the last place because in the growing of most farm plants a
knowledge of the functions of the flower is of less importance than
that of the roots, leaves and stems. However, a knowledge of these
parts is necessary for successful fruit culture and some other
horticultural industries.

As with the other parts of the plant our study will not be exhaustive
but will be simply an attempt to bring out one or two important truths
of value to most farmers.

In the study of flowers the specimens used for study will depend upon
the time of the year in which the studies are made and need not
necessarily be the ones used here for illustration.

FUNCTION OR USE OF FLOWERS TO PLANTS

Of what use is the flower to the plant?

You have doubtless noticed that most flowers are followed by fruit or
seed vessels. In fact, the fruit and seeds are really produced from
the flower, and the work of most flowers is to produce seeds in order
to provide for new plants.

[Illustration: FIG. 68.
A horse-chestnut stem showing leaves, buds, and scars where last
year's leaves dropped off.]

[Illustration: FIG. 69.--AN UNDERGROUND STEM
Buds show distinctly at points indicated by _b_.]

To understand how this comes about it will be necessary to study the
parts of the flower and find out their individual uses or functions.

PARTS OF A FLOWER

If we take for our study any of the following flowers: cherry, apple,
buttercup, wild mustard, and start from the outside, we will find an
outer and under part which in most flowers is green. This is called
the calyx (Figs. 70-74). In the buttercup and mustard the calyx is
divided into separate parts called sepals. In the cherry, peach and
apple, the calyx is a cup or tube with the upper edge divided into
lobes.

Above the calyx is a broad spreading corolla which is white or
brightly colored and is divided into several distinct parts called
petals. The petals of one kind of flower are generally different in
shape, size and col