Multivariate analysis of a reference collection of elm leaves

Analysis of leaf measurements of a reference collection of elm leaves suggests that the leaves, collected from trees which were selected by R. H. Richens as spanning the range of elm in Europe, fall into two primary groups. The first of these groups is made up of the representatives of the Wych elm (Ulmus glabra), which is known to be a distinct species. The second, larger, group is made up of an assemblage of subgroups that represent English elm (Ulmus procera), Ulmus minor and hybrids between Ulmus minor and Ulmus glabra. A minimum variance cluster analysis suggests that these subgroups are reasonably distinct, and discriminant analysis, logistic regression and a genetic algorithm are used to help identify the subgroups.