[§ 3.] PLAN OF FLOWER.
[239.] All flowers are formed upon one general plan, but with almost infinite variations, and many disguises. This common plan is best understood by taking for a type, or standard for comparison, some perfect, complete, regular, and symmetrical blossom, and one as simple as such a blossom could well be. Flowers are said to be
Perfect (hermaphrodite), when provided with both kinds of essential organs, i. e. with both stamens and pistils.
Complete, when, besides, they have the two sets of floral envelopes, namely, calyx and corolla. Such are completely furnished with all that belongs to a flower.
Regular, when all the parts of each set are alike in shape and size.
Symmetrical, when there is an equal number of parts in each set or circle of organs.
240. Flax-flowers were taken for a pattern in Section II. [16]. But in them the five pistils have their ovaries as it were consolidated into one body. Sedum, Fig. [222], has the pistils and all the other parts free from such combination. The flower is perfect, complete, regular, and symmetrical, but is not quite as simple as it might be; for there are twice as many stamens as there are of the other organs. Crassula, a relative of Sedum, cultivated in the conservatories for winter blossoming (Fig. [224]) is simpler, being isostemonous, or with just as many stamens as petals or sepals, while Sedum is diplostemonous, having double that number: it has, indeed, two sets of stamens.
Fig. 224. Flower of a Crassula. 225. Diagram or ground-plan of same.