Examine a number of flowers and find the parts.

FUNCTIONS OF THE PARTS OF THE FLOWERS

Now what are the uses of these parts of the flower?

[Illustration:  FIG. 70.—­FLOWER OF CHERRY. a, pistil; b, stamen; c, corolla; d, calyx; e, section of flower showing ovary with ovule. (Drawing by M.E.  Feltham.)]

[Illustration:  FIG. 71. 1.  Flower of apple; b, stamens; c, corolla; d, calyx. 2.  Section of same; a, style; e, compound ovary; f, filament; g, anther.  (Drawing by M.E.  Feltham.)]

[Illustration:  FIG. 72. A. Pistil of flowering raspberry; e, ovary; t, style; s, stigma. B. Stamen of flowering raspberry; f, filament; g, anther; p, pollen.]

[Illustration:  FIG. 73.—­FLOWER OF BUTTERCUP. c, petals; d, sepals; h, ripened pistils, or fruit. (Drawing by M.E.  Feltham.)]

If we watch a flower of the peach or cherry from week to week, we will see that the pistil develops into a peach or cherry which bears within a seed from which a new plant will be produced if the seed is placed under conditions necessary for germination or sprouting.

The pistils of the flowers of other plants will be found to develop into fleshy fruits, hard nuts, dry pods or husks containing one or more seeds.

The work of the pistil or pistils of flowers then is to furnish seeds for the production of new plants.

The botanists tell us that a pistil will not produce seeds unless it is fertilized by pollen from the same kind of flower falling on its stigma.

The work of the stamen then is to produce pollen to fertilize the pistils.  Pistils and stamens are both necessary for the production of fruit and seed.  They are therefore called the essential or necessary parts of the flower.

The botanists also tell us that nature has provided that in most cases the pistils shall be fertilized by the pollen of some other flower than their own, as this produces stronger seeds.

How is the pollen carried from flower to flower?

Go into the garden or field and watch the bees and butterflies flying about the flowers, resting on them and crawling into them.  They are seeking for nectar which the flower secretes.  As they visit plant after plant, feeding from many flowers, their bodies become more or less covered with pollen as they brush over the stamens.  Some of this pollen in turn gets rubbed off on the stigmas of the pistils and they become fertilized.  Thus the bees and some other insects have become necessary as pollen carriers for some of the flowers and the flowers in turn feed them with sweet nectar.

This gives us a hint as to one use of the corollas which spreads out such broad, brightly-colored, conspicuous petals.  It must be that they are advertisements or sign boards to attract the bees and to tell them where they can find nectar and so lead them unconsciously to carry pollen from flower to flower to fertilize the pistils.  The act of carrying pollen to the pistil is called pollination, and carrying pollen from the stamens of one flower to the pistil of another flower is called cross pollination.