"Two general conclusions can be reached from the comparison of flower development genes in two distantly related species. The first is that the basic mechanisms that define organ identity in developing flowers appear to be the same in both species. Genes exist whose mutants have similar phenotypes and similar interactions, and a single model can explain the action of these genes in both species."
January 1, 1970
https://en.wikiquote.org/wiki/ABC_model_of_flower_development