In the higher plants the flower is the expanded fruit-bud and is the organ of reproduction. A few plants under culture like the horseradish multiply rapidly by root extension, and nearly all plants can be propagated in other ways than from seed. Yet the flower in fruit- and nut-growing must precede the fruit.
A knowledge of the parts of the flower is needed by the modern strawberry- and grape-grower. It is also needed in crossing and in working with dioecious plants and trees. It is essential, too, in detecting varieties such as many of the plums that ripen the pistils before the pollen of that flower or tree is ready for their pollination.
The parts of flowers of different species vary materially. But the horticulturist who makes a brief study of the divided cherry-blossom in Fig. 13 will recognize the corresponding parts in the pea and most cultivated plants. The green part at the base marked (C) is the calyx. This is usually green in fruits. But in the tulip and other flowers it is colored.
The prominent organ rising in the centre marked (P) is the pistil with the ovary at the base. The flattened enlargement at the top is the stigma and the connecting slender part is the style. Some of the fruits have more than one pistil. The corolla marked "cor" is in the cherry and most flowers the colored part. In the cherry it has five divisions called petals. The stamens are marked (S). The enlarged part at the top is the anther containing the pollen. The slender part connecting the anther with the calyx is called the filament.
The young orchardist or gardener when able to identify and name the parts of the flower will usually give more attention to flower-structure and variation in some botanical treatise.
Fig. 13. - Divided cherry flower. (After Goff.)