Unequal Twins? Inflorescence Evolution in the Twinflower Tribe Linnaeeae (Caprifoliaceae s.l.)

Premise of research. Inflorescence morphology played an important role in the systematics of the twinflower tribe Linnaeeae. Recent molecular studies clarify systematic relationships among taxa and indicate that several genera and subgenera are not monophyletic. Using this molecular phylogeny as a backbone, we present detailed ontogenetic analyses of inflorescences in order to further elucidate the relationships among taxa and to understand the evolutionary history of morphological characters.Methodology. Fourteen taxa were studied using SEM and LM. Ontogenetic series were compared and character complexes described.Pivotal results. Emphasizing the importance of the epicalyx and flower orientation we show that flower pairs are not homologous. We also found that a reduction in sepal number occurred independently in Zabelia biflora, Diabelia serrata, and Abelia uniflora. This further supports the distinction between subtribes Zabeliinae and Linnaeinae. The study of anomalous specimens provides further insigh...