ABSTRACT
The flower is the product, indeed, the symbol, of the last group of plants to have evolved. It is certain that the flower is a structure which combines a protective envelope around the reproductive organs, the sexual cells, the pollen and ovules. Flower parts are only modified leaves. Pollination, the prelude to the fecundation or union of the male and female gametes, is accomplished by transportation of pollen grains from the anther of the stamen to the stigma (in angiosperm flowers). In the gymnosperms, pollen from the anther is taken directly to the ovule in the cone. The fusion of the gametes in the ovary will produce an egg which will develop into an embryo and, along with others parts, will form a seed. Insects and wind are the main pollinators of plants, helped by other mechanical means such as water in certain primitive flowers.
