Page:First course in biology (IA firstcourseinbio00bailrich).pdf/167

 flowering dogwood: here the real flowers are several, small and greenish, forming a small cluster in the center.

Essential Organs.—The essential organs are of two series. The outer series is composed of the stamens. The inner series is composed of the pistils. Stamens bear the pollen, which is made up of grains or spores, each spore usually being a single plant cell. The stamen is of two parts, as is readily seen in Figs. 173, 174,—the enlarged terminal part or anther, and the stalk or filament. The filament is often so short as to seem to be absent, and the anther is then said to be sessile. The anther bears the pollen spores. It is made up of two or four parts (known as sporangia or spore-cases), which burst and discharge the pollen. When the pollen is shed, the stamen dies.

The pistil has three parts: the lowest, or seed-bearing part, which is the ovary; the stigma at the upper extremity, which is a flattened or expanded surface, and usually roughened or sticky; the stalk-*like part or style, connecting the ovary and stigma. Sometimes the style is apparently wanting, and the stigma is said to be sessile on the ovary. These parts are shown in the fuchsia (Fig. 174). The ovary or seed vessel is at a. A long style, bearing a large stigma, projects from the flower. See also Figs. 175 and 176.

se, sepals; p, petals; sta, stamens; o, ovary; s, style; st, stigma. The pistil consists of the ovary, style, and stigma. It contains the seed part. The stamens are tipped with anthers, in which the pollen is borne. The ovary, o, ripens into the fruit.

Stamens and pistils probably are homologous with leaves. A pistil is sometimes conceived to represent anciently a