Question

In snapdragon (Antirrhinum majus), a cross between varieties with red and white flowers produces an all pink progeny. Explain how it is a case of incomplete dominance and not of blending inheritance.

Answer 1

In incomplete dominance the genes of an allelomorphic pair are not expressed as dominant and recessive but express themselves partially when present together in a hybrid and is an intermediate between the two genes. As a result an intermediate character is obtained. e.g., Two types of flowers occur in Mirabilis jalapa (4 o’ clock plant) and Antirrhinum majus (snapdragon/dog flower). The red flower colour is due to gene RR, white flower colour is due to gene rr but pink flower colour appears in case of genotype Rr.. 

It is not a case of blending inheritance because the parental characters reappear in the F₂ generation without any modification.