The Species Concept in Oenothera and Evolution of the Genus

Abstract

The observations on the phenotype of species hybrids in the genus Oenothera compared with recognized species are not compatible with the classical concept of “pure species” in taxonomy. All the investigations on species hybrids confirm the conclusion that was reached by Renner (1916, 1917), namely, that most Oenothera species are constant hybrids. From these considerations the question arises whether the classical species concept makes sense in Oenothera, or whether the Renner complexes are the real taxonomic units of this genus. They can be combined in different ways to give species. When treated in the usual taxonomic manner these seem to be “good species” for taxonomists. New species can arise whenever hybridization between existing species occurs (Cleland 1944; Renner 1946).