What is self-pollination?

Pollination is the transfer of pollen from the male part
of the plant, anther, to the female part, stigma. Pollination is necessary for
fertilization and reproduction, in other words, for the propagation of plants. It can be
either cross-pollination or self-pollination. 

In
cross-pollination, the transfer of pollen takes place from the flower of one plant to
that of another plant of the same species, usually by external means such as wind and
insects. In the case of self-pollination, the pollen transfer occurs within the same
flower. It is usually observed in legumes (such as peanuts), orchids, wheat, rice, oats,
etc. A relatively small amount of pollen is transferred from anther to stigma, as
compared to cross-pollination. Self-pollination leads to more uniform progeny and the
plant does not have to spend energy on attracting pollinators. It results in perfect
flowers as compared to cross-pollination, which causes both perfect and imperfect
flowers.