Studies of the anatomical structure of the stem and leaf, with special emphasis on the organization of the vascular system, has been carried out on 13 Aconitum species from Aconitum subgenera Aconitum, Anthora and Lycoctonum . All investigated species show a more or less mesomorphic anatomical structure, typical for other Ranunculaceae. Hence, these species have similar trilacunar three‐trace organization of the nodal vascular system. In the stem the vascular system is open (with weakly developed cambium) or closed collateral, and incomplete (consisting of the bundles were represented), large complete, middle‐size complete and small incomplete or with weakly developed xylem. The number of vascular bundles in petioles appear to have no taxonomical value. Nevertheless, it was found that the spatial organization of these vascular bundles in the petiole are of taxonomic importance. As a result, the investigated species can be divided into four main groups congruent with the current sectional and subgeneric division of the genus. The only exception was A. × cammarum ( A . sect. Acomarum ) in which the is identical to that of A . sect. Cammarum . The most primitive vascularization is found in A. anthora , while the most advanced one is found in A. variegatum . The highly differentiated and distinct nodal anatomy of A. anthora suggests a high, plausibly subgeneric, taxonomical rank of this species.