Self-incompatibility is a genetic mechanism in angiosperm that prevents self-pollination. It develops genetic incompatibility between individuals of the same species or between the individuals of different species.
The plants which exhibits this phenomenon have the ability to prevent germination of pollen grains and thus prevents the growth of the pollen tube on the stigma of the flower. This prevents the fusion of the gametes along the development of the embryo. As a result no seed formation takes place.