Sexual Reproduction in Flowering Plants — BIOLOGY STD 12 Science — Question

It a pllen grain from an anther happens to land on a stigma of a flowers on the same plant, a biochemical block prevents the pollen from completing its development and fertilizing and egg. This ability of plant to rejects its own pollen and that of closely related individuals is called self-incompatibility.
The self incompatible species prevent the germination of pollen grains and the growth of the pollen tube on their stigma. This prevents the fusion of the gametes and thus no embryo is formed. As a result, no seed formation takes place.