Page:Evolution of Life (Henry Cadwalader Chapman, 1873).djvu/137

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Flowers, among the most beautiful of nature's works, are always interesting to the laity and the botanist, offering objects of ornament and beauty to the one, and subjects for study and admiration to the other. The flower is the reproductive apparatus of the higher plants, made up of the organs by which the seed is produced, fertilized, and converted into the embryo plant. If we examine the flower of the Violet (Yellow Violet) (Fig. 130), the green cup-like arrangement of leaves first deserves our attention; this is known as the calyx, and the leaves composing it are called sepals. Within the calyx is seen another whorl of yellow leaves, known as petals; their union forms the corolla. Springing from the middle of the calyx and corolla, and standing erect, is seen a delicate tube, the pistil. Surrounding the pistil, and differing from it in appearance, are found the stamens. If the pistil is examined separately (Fig. 132), it is seen to be composed of the following parts: the head or stigma, the stalk or style, and the ovary. The ovary contains the ovule, or future seed, and if the ovule be magnified it is seen to contain the embryo-sac, and within the embryo-sac is found the germinal vesicle. The germinal vesicle is the rudiment of the future plant. The stamens, or stalks, surrounding the pistil, are composed of the stems or filaments supporting the anthers or little heads. The anthers contain the pollen, or fertilizing principle. Suppose the supreme power of Turkey to be a woman, and the Sultana to have a harem of men, such a condition of social life would represent what is seen in the Violet, or better in a section of the Morning-glory (Fig. 131), where the imaginary Sultana is realized in the pistil, the harem of men in the stamens. The pollen produced in the anthers finds its way to the stigma, or head of the pistil; from the head it passes down through the style, or tube of the pistil, until it reaches the ovary. Piercing successively the ovary, ovule, and embryo-sac, it finally comes in contact with the germinal vesicle. From this moment the life of the new plant begins in the formation of the embryo. The flowers of the Violet and Morning-glory serve to illustrate the reproductive apparatus of many plants. If, however, the flower of the Goose-foot (Chenopodium) (Fig. 133) be compared with that of the Violet, the absence of the corolla at once strikes the attention; and if the flowers of the Bread-tree, Pine, etc. (Fig. 135, a, b) be now examined, calyx and corolla are both found wanting. Further, in trees like the Pine, etc. there