Incompatibility is very common in plant kingdom was reported by

Incompatibility is very common in the plant kingdom as reported by Lewis.
Incompatibility is a physiological mechanism that enforces outbreeding. It is widespread throughout the families of flowering plants.
Incompatibility is due in some species to the failure of pollen germination, in others to the pollen tubes failing to penetrate the full length of the style.
Incompatibility in species crosses and their derivatives show that species without an incompatibility system have polygenic modifiers which weaken the action of the S gene.