Question

What is autogamy and geitonogamy?

Answer 1

Hint: Autogamy is a self-fertilization. It is a fusion of two gametes, which come from the same individual. It is a predominant form of self-pollination. It is a reproductive mechanism of flowering plants and some protists. E.g. Paramecium aurelia. Geitonogamy is also a type of self-fertilization. It does not happen on the same flower, but happens on different flowers on the same plant. E.g. Cucurbita maxima.

Complete answer
Both Geitonogamy and autogamy are types of self-pollination, which is required for double fertilization. Autogamy is represented by the transfer of pollen grain to the stigma from the anther in the same flower. Geitonogamy is represented by the transfer of pollen grain from the anther to the stigma of some other flower of the same plant. The pollinating agents are wind, bats, water, insects, birds and animals.
Autogamy does not require a pollinating agent, whereas geitonogamy always requires a pollinating agent. Autogamy is a type of self-fertilization, while geitonogamy is a type of functionally cross pollination.
There are some differences between autogamy and geitonogamy

Characteristic	Autogamy	Geitonogamy
Type of pollination	Self-pollination	Genetically self-pollination, but functionally cross-pollination
Adaptation	Favored before the opening of flower	On a single stem, presence of multiple flowers
Pros and Cons	No energy wastage	Energy wasted on pollinating attractants
Examples	Sunflowers, Tridax, orchids	Corn, maize

Note:
Some similarities are present between autogamy and geitonogamy. They are as follows:
1. Both are self-pollination processes.
2. Both occur in flowering plants.
3. In both cases, identical offspring to parents are obtained.
4. Both occur in the same plant.
5. Both do not contribute to evolution as they produce genetically identical progenies.