Solution

Self-incompatibility is the condition in which pollen from the same plant cannot pollinate the flower. Thus, self-incompatibility imposes complete restriction on autogamy. This evolution might have occurred in order to prevent too much inbreeding because continuous inbreeding prevent variations. In such plants, cross pollination is the norm and pollen from a plant pollinates the flower on another plant. This ensures accumulation of gene pools from two different plants.