Fremdpollinierung

Fremdpollinierung, also known as cross-pollination, is a type of sexual reproduction in plants. It involves the transfer of pollen from the anther of one flower to the stigma of another flower. This transfer can occur between flowers on the same plant or between flowers on different plants, although typically the latter is implied when discussing the evolutionary advantages. The key distinction from self-pollination is that the pollen originates from a genetically distinct individual.

For cross-pollination to be successful, the pollen must be compatible with the stigma of the recipient flower. This compatibility is often determined by genetic factors. Various mechanisms have evolved in plants to promote cross-pollination and prevent self-pollination. These include the physical separation of male and female reproductive parts within a flower (herkogamy), differences in the timing of pollen release and stigma receptivity (dichogamy), and self-incompatibility systems, where the plant actively prevents its own pollen from fertilizing its ovules.

The agents of cross-pollination are diverse and include wind (anemophily), water (hydrophily), insects (entomophily), birds (ornithophily), and other animals. Plants often develop specific adaptations to attract their particular pollinators, such as bright petals, nectar, and scent.

Cross-pollination generally leads to increased genetic diversity within a plant population. This genetic variation can enhance a species' ability to adapt to changing environmental conditions, resist diseases, and maintain vigor. In contrast, obligate self-pollinators, which primarily reproduce with their own pollen, may experience reduced genetic diversity and a greater susceptibility to inbreeding depression.