Understanding Pollination and Pollen Transfer

Pollination is a crucial process in the life cycle of many plants. It involves the transfer of pollen grains from the anther (male part) of a flower to the stigma (female part) of the same or another flower. This transfer is necessary for fertilisation to occur and seeds to develop.

The question describes a specific type of pollen transfer: from an anther of one flower to the stigma of a flower on a different plant. Let's examine the given options to identify the correct term for this process.

Analyzing the Options

• Fertilisation: Fertilisation is the fusion of the male gamete (from the pollen grain) with the female gamete (within the ovule) to form a zygote. It happens after pollination and pollen tube growth. It is not the transfer of pollen grains itself.
• Gettologamy (Geitonogamy): This term, likely intended as Geitonogamy, refers to the transfer of pollen from the anther of one flower to the stigma of another flower on the same plant. Although it involves different flowers, it is genetically equivalent to self-pollination because the pollen comes from the same individual plant.
• Xenogamy: This term refers to the transfer of pollen from the anther of a flower on one plant to the stigma of a flower on a different plant of the same species. This type of pollination brings genetically different pollen to the stigma, promoting genetic variation. It is also known as cross-pollination.
• Cleistogamy: This describes a condition in which flowers do not open at all. Pollination occurs within the closed flower, ensuring self-pollination. This is not the transfer of pollen between different plants.

Conclusion: Identifying Xenogamy

Based on the definitions, the transfer of pollen grains from an anther of one flower to the stigma of a flower of a different plant precisely matches the definition of Xenogamy.

Therefore, the correct answer is Xenogamy.

Revision Table: Types of Pollination

Additional Information: Importance of Xenogamy

Xenogamy, or cross-pollination, is very important for many plant species. Here's why:

• Genetic Diversity: It introduces genetic variation into the population. Offspring produced through xenogamy are hybrids, combining genes from two different parent plants. This diversity can help the species adapt to changing environmental conditions, resist diseases, and improve vigor.
• Avoiding Inbreeding Depression: Repeated self-pollination (autogamy or geitonogamy) can lead to inbreeding depression, where undesirable recessive traits become more common and the health and vigor of the population decline. Xenogamy helps prevent this by introducing new genetic material.
• Evolution: Genetic variation provided by xenogamy is the raw material for evolution by natural selection.

Many plants have developed specific mechanisms to promote xenogamy and prevent self-pollination, such as different timing of male and female flower part maturity (dichogamy), physical separation of anthers and stigmas (herkogamy), or genetic self-incompatibility systems.