Despite considerable variation within taxa, it was possible to establish taxon-specific responses as several seed batch per taxa were used. Present suggestions for seed dormancy classifications were not helpful for revealing differences in seed dormancy pattern, germination preferences and dormancy strength, at least not in an ecologically meaningful way. In an evolutionary perspective, we conclude that the general dormancy pattern is a conservative character for these Papaver taxa, that germination temperature preferences have been adjusted when or after new taxa evolved, and that dormancy strength is the most easily changeable character involved in germination. The general dormancy pattern explains how the taxa can perform as winter annuals in warmer climates, but mainly as summer annuals in colder climates. Hence, there is no need to infer local adaptations when interpreting within-taxon differences in temporal patterns of seedling emergence. Furthermore, the results suggest that the expected climatic change in cold temperate areas, from cooler to warmer, will lead to a transformation of Papaver phenology from a substantial fraction of summer annuals to mainly winter annuals.