Unilateral Incompatibility

This relates to incompatibility that operates in one direction. The most common way to ascertain unilateral incompatibility is to perform crosses between a self-incompatible species and a self-compatible species. The cross is successful only when the self-compatible species serves as the female parent. This kind of incompatibility also operates between species of different genera. Unilateral incompatibility can be explained on the following basis:

Table:  Inter specific incompatibility - Passive rejection and possible mechanisms