Non-equivalency of genera inAngiospermae: Evidence from DNA hybridization studies

The problem of taxa equivalency in phylogenetically distant groups can hardly be solved by comparing morphological differences alone. An attempt is made to approach the problem by means of DNA comparisons, e.g., DNA hybridization. Data obtained forCompositae, Umbelliferae andIridaceae indicate that both unique and repetitive DNA sequence comparisons lead to the conclusions that genera within these families are not equivalent, e.g., the differences in the DNA among the species ofIris are much more pronounced than among those ofAchillea; some genera ofUmbelliferae occupy an intermediate position.