396. Technical definition of the flower. The flower is an assemblage of leaves more delicately and variously formed, borne at the upper nodes of the axis' where the internodes are undeveloped. This portion of the axis is called
397. The receptacle or torus. It is the axis of the flower situated at the summit of the flower-stalk. Its form above is commonly that of a flattened or somewhat conical disk, the center of which corresponds with the apex of the axis.
398. The flower may consist of the following members: 1, the floral envelops; 2, the essential floral organs.
399. The floral envelops consist of one or more circles or whorls of leaves surrounding the essential organs. The outer of these whorls is called the calyx and the other, if there be any, the corolla. The calyx may, therefore, exist without the corolla, but the corolla can not exist without
400. The calyx. This is a Greek word signifying a cup. It is applied to the external envelop of the flower, consisting of a whorl of leaves with their edges distinct or united, usually green, but sometimes highly colored. The calyx leaves are called sepals.
257, Flower of the strawberry. 25S, Flower of the pink. 259, Flower of the lily (Lilium su-perbum). The pupil will point out the parts.
401. Corolla is a Latin word signifying a little crown, applied to the interior envelop of the flower. It consists of one or more circles of leaves, either distinct or united by their edges, usually of some other color than green, and of a more delicate texture than the calyx. Its leaves are called petals.
402. Perianth (πέρі, around, avθoς, flower) is a word in common use to designate the floral envelops, as a whole, without distinction of calyx and corolla. It is used in description, especially when these two envelops are so similar as not to be readily distinguished, as in the tulip, lily, and the endogens generally; also where only one envelop exists, as in Phytolacca, elm, etc. (259, per.)
403. The essential floral organs stand within the circles of the perianth, and are so called because they are the immediate instruments in perfecting the seed and thus accomplishing the final purposes of the flower. These organs are of two kinds, perfectly distinct in position and office; viz., the stamens and the pistils.
404. The stamens are those thread-like organs situated just within the perianth and around the pistils. Their number varies from one to a hundred or more; but the most common number is five. Collectively they are called the androecium (avδρες,* stamens, oíĸος, a house).
405. The pistils (called also carpels) oecupy the center of the flower at the absolute terminus of the flowering axis. They are sometimes numerous, often apparently but one, always destined to bear the seed. Collectively they are called the gynoecium (yvvή, pistil, oíĸος).
* The plural of avήp, a man, a term applied to the stamen by Linnaeus in accordance with his favorite theory of the sexes of plants. The term yuvή, woman, is, on the same ground, applied to the pistil.
406. Recapitulation. Thus we have noticed the members of the flower in the order of their succession from the outer to the inner circle. Now, in regard to the receptacle on which they stand in concentric whorls, we find (reversing the order) the gynoecium in the midst, the center of the flower, the androecium encircling it, the corolla next without, and the calyx embracing the whole.
407. Appendages. These are the four proper members or sets of organs composing the flower. Occasionally we meet with a fifth between the corolla and stamens, not easily referrible to either, like the scales in the throat of the Borrageworts, or the crown of the Narcissus and jonquils. Such are regarded as appendages, not necessary to the completeness of the flower.