Linked from
The 14 pages that link to Self-incompatibility, each with the reason it gives.
Pollen tubeRelated: It can stop pollen tubes before they reach the ovules.
Self-pollinationCompared with: It blocks self-pollen even when pollen reaches a receptive stigma.
FloretRelated: It can shape mating among florets within a head and between plants.
Brassica napusRelated: Its presence or loss in crop lines influences whether plants self-pollinate.