Pollen represents the male element of reproduction in seed plants. The
flowering plants are normally reproduced by seed. Fertilization is
brought about by the intervention of the grains of pollen which are
borne by the stamens or male organs. In the corn plant the stamens are
produced in the tassels where pollen is developed in great abundance.
The pistils, or female organs, are represented by the silks attached
to the ear. There is a separate silk attached to each kernel, and each
must be separately fertilized. In many plants both stamens and pistils
occur in the same blossom, as is the case with apples, pears, etc. In
some cases the stamens or male organs are borne on a separate plant or
tree, as is the case with the persimmon. Cucumbers have the separate
organs in separate flowers. In order to insure fertilization it is
necessary that the pollen grains be carried from the stamens to the
pistils. In the grasses and similar plants this is usually accomplished
by the wind, while in most fruits, insects are the principal agents.
Pollen grains are very minute and are produced in small sacs in the
tip of the stamen, commonly called anther. When ripe, the breaking of
the sac sets the grains free in great abundance. A single grain is
sufficient to fertilize an ovule and produce a seed; yet, because of
the distance between the stamens and pistils, large quantities of the
pollen or flower dust are necessary to insure pollination. Ragweed and
corn produce pollen in such abundance that one brushing by the plants
is dusted so freely as to appear to be covered with flour.
Pollen is of special importance to the beekeeper, since it serves as
food for young bees. It is the sole source of nitrogenous food for the
growing larvæ, and is stored in large quantity in the open cells of
the brood combs. Without an abundance of pollen available for food for
the developing brood, the colony cannot prosper. Pollen is second only
in importance to surplus honey to the beekeeper, and an abundant supply
of plants which yield pollen during the brood-rearing season is very
desirable.