Sexual Organs of Plants.--As already remarked, flowers are the sexual organs of plants. Nothing is more interesting in the natural world than the wonderful beauty, diversity, and perfect adaptability to various conditions and functions, which we see in the sexual parts of plants. An exceedingly interesting line of study, which has occupied the attention of many naturalists, is the wonderful perfection displayed in the adaptability of the male and female parts of plants to each other. Without burdening the reader with unnecessary technicalities of detail, we will briefly notice the principal parts of vegetable sexual organs as illustrated in flowers. Complete flowers are made up of four parts, two of which, the _stamen_ and _pistil_, are essential, while the other two, the calyx and corolla, are accessory. The _calyx_ is that part which surrounds the flower at its outer and lower part. It varies greatly in form and color, but is most frequently of a green or greenish color. Just within the calyx is the _corolla_, which usually forms the most attractive, showy, and beautiful part of the flower. The beautifully colored petals of the rose, geranium, dahlia, and other similar flowers, form their corollas. Vegetable Husbands.--Within the cup formed by the calyx and corolla are placed the _stamens_ and _pistils_ of the flower, the first being the male organs proper, and the second the female organs of the flower. The stamen is composed of a stem or filament, at the summit of which are placed two little sacks called the _anther_, which contain a fine, microscopic dust, the _pollen_, which contains the male reproductive element of the flower. This part of the plant corresponds to the male organ of reproduction in animals. A stamen has been called, not inaptly, a vegetable husband. Some flowers have many stamens, or vegetable husbands, which reminds us of the custom in Thibet and some other Eastern countries which allows a woman to have several husbands. Polygamous Flowers.--The great naturalist, Linnaeus, whose name was immortalized by his careful study and classification of organized life, made the number of stamens possessed by various flowers the basis of a systematic classification. For example, a flower having but one stamen was classed as _monandria_, which means, literally, one husband; one having two stamens was classified as _diandria_; flowers having a large number of male organs were termed _polyandria_, or many husbands. The Female Organ of Flowers.--The _pistil_ occupies the very center of the flower. It produces and contains in a cell, the female element, termed the _ovule_. It is surmounted by the _style_ and the _stigma_. A series of plants in which the sexual organs are not visible to the eye are termed _cryptogamia_, which means literally, hidden marriages.