Flower is the characteristic reproductive structure of plants called spermatophytes or phanerogams. The function of a flower is to produce seed through sexual reproduction. For plants, seeds are the next generation, and serve as the primary means through which species perpetuate and propagate.
All spermatophytes have flowers that will produce seeds, but the internal organization of the flower is very different in the two main groups of spermatophytes: living gymnosperms and angiosperms .
Parts of the flower
National flower of all countries can have different colors, but, also, several shapes and sizes. The rafflesia, for example, is the plant with the largest flower in the world: it weighs 7 kilograms and measures almost 1 meter. Sometimes the flowers appear solitary at the end of the stem or branch; but, in other occasions, several flowers are grouped and form an inflorescence; is what happens with hydrangeas.
The flower is always a terminal branch consisting of a modified stem: the floral axis or receptacle. The floral axis carries between one and four types of specialized appendices or modified leaves, usually arranged in whorls in the most evolved flowers and in spirals in the most primitive. In a typical flower, the outer whorl or chalice is formed by several sepals that protect the flower bud before it opens. The next whorl of the floral receptacle is the corolla, composed of several petals; in many cases, it carries nectar-producing glands to attract pollinators see Nectar; Polarization. The next whorl, the androceo, groups several stamens, that produce in the anthers the necessary pollen for the reproduction; There may be two whorls of stamens. The innermost whorl is the gynoecium, formed by several carpels, in many cases soldiers in a pistil. Each carpel contains at least one placenta in which the immature seeds or ova are inserted. Chalice and corolla together form the perianth.
The fragrance of flowers has its origin in the formation of small amounts of volatile oils by alteration of the essential oils contained in the petals. The natural perfumes are made with flowers such as hyacinth, heliotrope, mimosa, jasmine, orange blossom, rose and violet. Fragrances attract pollinators. Some flowers exhale putrid odors, also to attract pollinators, in this case flies of the meat or other insects next to them; These fragrance of flowers like decaying flesh and are not grouped within a special family or order within the flowering plants.