Primula is an ideal example of hetero-morpha sporophytic system of incompatibility, where two types of flowers, pin and thrum, are observed. The compatible mating is observed in the crosses of

Primula is an ideal example of a heteromorphic sporophytic system of incompatibility, where two types of flowers, pin and thrum, are observed. The compatible mating is observed in the crosses of Pin × thrum flowers of its reciprocals.
Primula is a complex and varied genus, with a range of habitats from alpine slopes to boggy meadows.
In heteromorphic system, flowers of different incompatibility groups are different in morphology. For example, in Primula there are two types of flowers, pin, and thrum. Pin flowers have long styles and short stamens, while thrum flowers have short styles and long stamens.