§ 2 Parts or Organs of the Flower
228. These were simply indicated in Section II. 16. Some parts are necessary to seed-bearing; these are Essential Organs, namely, the Stamens and Pistils. Others serve for protection or for attraction, often for both. Such are the leaves of the Flower, or the Floral Envelopes.
229. The Floral Envelopes, taken together, are sometimes called the Perianth, also Perigone, in Latin form Perigonium. In a flower which possesses its full number of organs, the floral envelopes are of two kinds, namely, an outer circle, the Calyx, and an inner, the Corolla.
230. The Calyx is commonly a circle of green or greenish leaves, but not always. It may be the most brightly colored part of the blossom. Each calyx-leaf or piece is called a Sepal.
231. The Corolla is the inner circle of floral envelopes or flower-leaves, usually of delicate texture and colored, that is, of some other color than green. Each corolla-leaf is called a Petal.
232. There are flowers in abundance which consist wholly of floral envelopes. Such are the so-called full double flowers, of which the choicer roses and camellias of the cultivator are familiar examples. In them, under the gardener’s care and selection, petals have taken the place of both stamens and pistils. These are monstrous or unnatural flowers, incapable of producing seed, and subservient only to human gratification. Their common name of double flowers is not a sensible one: except that it is fixed by custom, it were better to translate their Latin name, flores pleni, and call them full flowers, meaning full of leaves.
233. Moreover, certain plants regularly produce neutral flowers, consisting of floral envelopes only. In Fig. 214, some are seen around the margin of the cyme in Hydrangea. They are likewise familiar in the Hobble-bush and in Wild-Cranberry tree, Viburnum Oxycoccus; where they form an attractive setting to the cluster of small and comparatively inconspicuous perfect flowers which they adorn. In the Guelder Rose, or Snow-ball of ornamental cultivation, all or most of the blossoms of this same shrub are transformed into neutral flowers.
234. The Essential Organs are likewise of two kinds, placed one above or within the other; namely, first, the Stamens or fertilizing organs, and second, the Pistils, which are to be fertilized and bear the seeds.
235. A Stamen consists of two parts, namely, the Filament or stalk (Fig. 219 a), and the Anther (b). The latter is the only essential part. It is a case, commonly with two lobes or cells, each opening lengthwise by a slit, at the proper time, and discharging a powder or dust-like substance, usually of a yellow color. This powder is the Pollen, or fertilizing matter, to produce which is the office of the stamen.
236. A Pistil (Fig. 220, 221) when complete, has three parts; Ovary, Style, and Stigma. The Ovary, at base, is the hollow portion, which contains one or more Ovules or rudimentary seeds. The Style is the tapering portion above: the Stigma is a portion of the style, usually its tip, with moist naked surface, upon which grains of pollen may lodge and adhere, and thence make a growth which extends down to the ovules. When there is no style then the stigma occupies the tip of the ovary.
237. The Torus or Receptacle is the end of the flower-stalk, or the portion of axis or stem out of which the several organs of the flower grow, upon which they are borne (Fig. 223).
238. The parts of the flower are thus disposed on the receptacle or axis essentially as are leaves upon a very short stem; first the sepals, or outer floral leaves; then the petals or inner floral leaves; then the stamens; lastly, at summit or centre, the pistils, when there are two or more of them, or the single pistil, when only one. Fig. 223 shows the organs displayed, two of each kind, of such a simple and symmetrical flower as that of a Sedum or Stonecrop, Fig. 222.