Pollination

Pollination, the transfer of fertilizing pollen from the place of its formation (the anther) to the receptive part of the female organ (the stigma). The result of pollination is fertilization and the development of the plant's seed. Two types are distinguished: 1) self-pollination - the transfer of pollen within the same flower, and 2) cross-pollination - the transfer of pollen to another flower of the same or different plant. The latter is more common. In the case of bisexual flowers (which occur more frequently than unisexual ones), self-pollination is usually prevented either by special structures in the flower or by the asynchronous maturation of the male and female sexual organs within it. The significance of cross-pollination lies mainly in the hybridization that occurs when sexual elements of different origins and possibly different genetic compositions are combined. In some cases, self-pollination either fails to produce seed development at all or produces fewer seeds of inferior quality. However, there are many plants that normally self-pollinate and nevertheless show no signs of degeneration (for example, wheat, barley, etc.). In the case of cross-pollination, pollen is usually carried either by the wind (anemophilous plants) or by animals, especially insects (zoophilous, specifically entomophilous plants). Anemophilous plants usually have small, inconspicuous but numerous flowers, and produce pollen in enormous quantities (for example, in birch, poplar, etc.). Conversely, entomophilous flowers are often large, brightly colored, fragrant, and contain a special sugary juice (nectar) inside. All this attracts insects that fly from flower to flower in search of food and carry the pollen adhering to their bodies. There is a very close correspondence between the structure of the flower and the visiting insect, ensuring this function is performed most reliably. This is considered one of the best examples of adaptations (Darwin).