In snapdragons, there is the red allele (R) and the white allele (W). There is no dominance between these alleles and when they are both together in a heterozygous individual (RW) it will produce pink offspring. This is because of incomplete dominance which is sometimes known as blending inheritance. In this example, if you cross a homozygous red flower (RR) with a homozygous white flower (WW) the only gametes each will contribute is an R or W to the offspring. This will result in 100% pink offspring in the F1 generation.