We studied characteristics of basal leaves of Trollius europaeus L. and T. altissimus Crantz, including blade morphology, phenolic acids and flavonoids. We also verified the influence of site conditions on leaf structure. Co-chromatography showed mostly quantitative differences in the contents of particular phenolic acids and flavonoids in leaves. Similarly, there were no important morphological differences between the species and with respect to some traits a significant distinction appeared within T. altissimus populations. Additionally, site conditions had an effect on leaf morphology of both examined species. Therefore, based on our results, the separation of two Trollius species is questionable. The study supported the statement that T. europaeus and T. altissimus are not separated species, thus T. europaeus should be divided into two lower taxa in the rank of variety or subspecies.