Anatomical characterisation of Euphorbia L. taxa from Serbia: implications for taxonomy and identification

This study examines the anatomical variability of stem and leaf traits and their taxonomic significance in 11 Euphorbia species and subspecies from Serbia, six of which (E. epithymoides, E. niciciana, E. serpentini, E. spinosa subsp. glabriflora, E. subhastata, and E. thessala) are investigated for the first time. A total of 31 quantitative anatomical characters were measured and analysed using univariate and multivariate statistical analyses. Key differentiating traits included stem diameter, stem collenchyma thickness, cortex parenchyma thickness, xylem thickness, width of stomata on the adaxial side, and stomatal surface area on the abaxial side. The findings underscore the diagnostic value of quantitative anatomical traits for taxa identification. Additionally, qualitative traits - particularly epidermal features such as indumentum, cell wall patterns, and stomatal types - further aid in taxa differentiation. This study provides the first comprehensive anatomical analysis of stems and leaves for most of the taxa examined, enhancing the understanding of Euphorbia variability patterns. It supports more precise taxa delimitation within the genus and establishes a foundation for future research.