The reproduction process in which fertilization occurs within a single plant is called self-pollination.

Here's a breakdown:

* Self-pollination: Pollen from the anther (male part) of a flower is transferred to the stigma (female part) of the same flower, or another flower on the same plant.

* Cross-pollination: Pollen is transferred from the anther of one plant to the stigma of a different plant of the same species.

Self-pollination can occur in plants that have both male and female reproductive parts (perfect flowers) or in plants that have separate male and female flowers on the same plant (monoecious).