In the four O’clock plant and snapdragons there is no dominance that its, heterozygous condition (Mirabili’s jalapa) expresses neither white nor red flower but produces pink flowers.
A red flowered 4’0 clock plant is crossed with a white flowered 4’0 clock Plant. The F, generation plant which is heterozygous yield’s pink flowers. It appears in this case, as if the characters have been blended. But when F2 generation is raised both red and white flowered plants together with pink flowered plants appear in the ratio of 1 Red; 2 Pink: 1 white. In F1 generation, in plant Rr, neither of the genes are dominant, both express their characters. For the expression of red colour, R is to be present in two sets similarly for white colour r is to be present in two doses. Since both R and r genes are present pink colour is expressed in F1 generation.