Quantitative and qualitative differences in morphological traits of endocarps revealed between Cornus L. species

Abstract

The genus Cornus encompasses a wide range of attractive wild taxa, often used as ornamental plants in landscaping. The aim of this investigation was to highlight the quantitative and qualitative diversity within endocarp morphological traits apparent among 15 Cornus species representing different geographical and phylogenetic groups. Seventeen morphological traits of Cornus endocarps were evaluated in 185 Cornus collections originating from the Northern Hemisphere. To explore structure in our dataset and reduce its complexity, several multivariate statistical analyses (i.e., PCA, MANOVA, ANOVA, and analysis of contingency tables) were employed. Two clearly distinct sample groups were observed after the PCA, reflecting a high level of taxonomic division of analyzed species, i.e., subgenera: Mesomora and Kraniopsis. The study highlights qualitative and/or quantitative characters that partitioned (1) groups of species or some individual species, (2) geographical groups, and (3) cultivated and wild collections. Results of trait validation are presented in identification keys. A partial congruence was detected between our results and a currently available species level phylogeny of the genus Cornus. The morphology of Cornus endocarps is of taxonomic importance and provides a key for species identification. The existence of only subtle morphological differences between some closely related taxa does not sufficiently explain their species status. The applicability of our results to the previously published morphological records is limited, mainly due to vague terminology. Considerably more work will need to be done to determine the effect of cultivation on qualitative reproductive traits of Cornus species.