Question

Mention any four strategies adopted by flowering plants to prevent self-pollination.

Answer 1

Self-pollination is the process where a flower contains anther and stigma and the pollen from the anther fertilizes the stigma.

Complete answer:
A bisexual flower contains both male and female reproductive parts. Such flowers self pollinate by autogamy i.e. the pollen from the anther of the same flower will fertilize the stigma of the same flower. When one flower pollinates another flower of the same plant then it is geitonogamy. But self-pollination is restricted to inbreeding which leads to the reduced population as they are more prone to extinction. Therefore, many flowers avoid self-pollination by some strategies that include; Dichogamy in which the maturation time of anther and stigma differs. If anther matures before the stigma it is said to be protandry, for example, Malvaceae while stigma matures before anther then it's protogyny. Aristolochia is an example of protogyny. Self sterility is when pollen in the other of a flower fails to fertilize the same flower or other flowers of the same species. An example includes orchids in which the flower wither away if pollinated by its own pollen; self-incompatible also called interspecies incompatibility is a genetic mechanism by which some plants recognize and reject their own pollen l, this forces outbreeding. It is also defined as a plant's inability to produce functional gametes to set seed for self-pollination. Dicliny is those bearing unisexual flowers. It may either have males on the same flower or a female on the same flower. Geitonogamy is the only alternative to such plants.

Note: In self-pollination, there is no genetic diversity, unlike cross-pollination. More diversity leads to better protection against extinction.Cross-pollination leads to greater genetic diversity because the microgametophyte and megagametophyte are derived from different plants.