Taxonomic status of Aster, Galatella and Tripolium (Asteraceae) in view of anatomical and micro-morphological evidence

Using light and scanning electron microscopy (SEM), comparative analyses of anatomical and micro-morphological characteristics of the leaf, stem and peduncle have been carried out on five species of the family Asteraceae (Aster amellus, Galatella linosyris, G. cana, G. sedifolia and Tripolium pannonicum), previously included in Aster although more recent morphological and phylogenetic studies indicate that Galatella and Tripolium should be considered as separate genera. The aim of the present study was to establish whether these species could be differentiated by anatomical characters. Our results will further inform the decision to separate the four aforementioned species from the genus Aster, as well as indicate whether anatomical data confirm the proposed circumscription of the genera Galatella and Tripolium. The anatomical observations and data analyses using discriminant and correspondence analysis showed that the combination of selected qualitative and quantitative characters separated the species into three groups, corresponding to the three genera. The characters of the leaf blade, its epidermis in particular, proved to be of the highest significance for discrimination at generic rank. The specific qualitative features that characterize each of the species and the genera were emphasized. Our findings support the attribution of the examined species to three genera, which proved to be anatomically distinguishable and well defined.