Hint: Self-pollination is the process of fertilization of the gynoecium with the anthers of the same flower or of different flowers of the same plant. The self-pollinated flowers do not depend on any agent for their pollination. So, they have an upper edge over cross-pollinated plants.
Complete answer: Self-pollination is the process in which pollen from the same plant arrives at the stigma of a flower or at the ovule. There are two types of self-pollination –
1. Autogamy – Here, pollen is transferred to the stigma of the same flower.
2. Geitonogamy – Here, pollen is transferred from the anther of one flower to the stigma of another flower on the same plant, or from microsporangium to ovule within a single (monoecious) gymnosperm.
Some plants have mechanisms to ensure autogamy, such as flowers that do not open (cleistogamy), or stamens that move and come in contact with the stigma.
Both hermaphrodite and monoecious plants have the potential for self-pollination which leads to self-fertilization unless there is a mechanism to avoid it. Plants that perform self-pollination include several types of orchids and sunflowers. Dandelions are capable of self-pollination as well as cross-pollination.
Advantages of self-pollination include –
1. If a given genotype is well-suited for an environment, self-pollination keeps this trait stable in the species.
2. Not depending on pollinating agents allows self-pollination to occur when bees and wind are nowhere to be found.
3. There is less wastage of pollen.
4. Self-pollinating plants do not depend on external carriers.
5. Pure breeds can be maintained easily.
6. The processes of production of nectar, scent, or colorful flowers in order to attract pollinators are also done away with.
Note: The process of strict self-pollination has been observed in closed flowers. This facilitates energy conservation in plants. The energy conservation by the flower is because it does not need to attract any pollinators.