Studies in Crataegus series Coccineae. I. Delimitation of series

The conventional concept of Crataegus series Coccineae was used as an hypothesis to test its validity when subjected to a morphometric analysis. Putative outgroups Crataegus ellwangeriana Sarg., ser. Molles, and ser. Dilatatae were included to test the limits of ser. Coccineae, and more distantly related ser. Punctatae and ser. Crataegus were included to provide scale. Multivariate studies based on substantial sample sizes and attribute lists were used to determine optimal group structure. We demonstrate that the group customarily called ser. Coccineae is cohesive. Crataegus ellwangeriana clearly proves to be outside of ser. Coccineae as are the close outgroups ser. Molles and ser. Dilatatae.