It shows incomplete dominance. In a cross between true-breeding red-flowered (RR) and true-breeding white-flowered plants(ww) in generation we get pink(Rw) flowers. We get 1:2:2(Red:Pink:White) ratio of flowers.Genetype ratio was exactly as we would expect, but phenotype ration had changed from 3:1 ratio. This is because R was not completely dominant over r and it made it possible to distinguish Rw as pink from RR (red) and ww (white).