The correct answer is Option (3)- Xenogamy.
There are three types of pollination described: autogamy, geitonogamy, and xenogamy.
- Autogamy: Autogamy refers to the transfer of pollen grains from the anther to the stigma of the same flower. It occurs within a single flower, and genetically, it involves the self-pollination of the plant. In autogamy, the pollen grains and stigma of the same flower come into contact, leading to fertilization with genetically identical pollen.
- Geitonogamy: Geitonogamy involves the transfer of pollen grains from the anther to the stigma of another flower of the same plant. While functionally it is a form of cross-pollination since it involves a pollinating agent, genetically it is similar to autogamy because the pollen grains come from the same plant. Geitonogamy does not introduce genetically different pollen to the stigma.
- Cleistogamous flowers which do not open at all. In such flowers, the anthers and stigma lie close to each other. When anthers dehisce in the flower buds, pollen grains come in contact with the stigma to effect pollination. Thus, cleistogamous flowers are invariably autogamous as there is no chance of cross-pollen landing on the stigma. Cleistogamous flowers produce assured seed-set even in the absence of pollinators.
- Xenogamy: Transfer of pollen grains from anther to the stigma of a different plant .This is the only type of pollination which during pollination brings genetically different types of pollen grains to the stigma.
Xenogamy is an important mechanism for promoting genetic diversity in flowering plants. It allows for the exchange of genetic material between different individuals, which can enhance the adaptability and survival of the species. Biotic agents such as insects, birds, or mammals are often involved in facilitating xenogamy by carrying pollen from one plant to another. |
