Comparative morpho-anatomical study of the native Fritillaria species from Romania and its taxonomic significance

• Comparative anatomy of native Fritillaria species from Romania is presented • Diagnostic structural differences found in roots, stems, leaves, and tepals • Anatomical traits reflect ecological adaptations and support identification • A dichotomous key is proposed using distinct anatomical characteristics • First anatomical study conducted on Fritillaria meleagroides This study investigated the native Fritillaria species of Romania, Fritillaria montana Hoppe ex W.D.J. Koch (mesophilous), Fritillaria meleagris L. (meso-hygrophilous), and Fritillaria meleagroides Schult. & Schult. fil. (halo-hygrophilous). Fritillaria montana and Fritillaria meleagris are protected in Romania, whereas Fritillaria meleagroides is newly recorded in the national flora. Field identification of these taxa relied on morphological traits visible during the reproductive period. The study examines the vegetative organs (roots, bulbs, stems, and leaves) to provide a detailed understanding of species morpho-anatomy and to aid taxonomic identification outside the flowering phase. Given their differing ecological requirements, particular focus was on structural variation related to soil moisture conditions. Morphological measurements were complemented by anatomical analyses of cross-sections and paradermal sections (leaf) examined under optical microscopy. Morphological differences among taxa were minor, whereas anatomical analyses revealed distinct histological features in all vegetative organs. Key traits include the presence or absence of aeriferous cavities in the root cortex and bulb storage parenchyma; variation in aeriferous formations in the stem medullary parenchyma; dimensional variation in stem parenchyma; numerical and dimensional differences in conductive bundles; presence or absence of perifascicular sheaths in the lamina; and differences in lamina cross-section outline. Anatomical traits linked to moisture preference, particularly the occurrence of aeriferous formations, proved most informative for distinguishing species outside the reproductive period. These features formed the basis of a dichotomous identification key, designed for use under optical microscopy. The key enables reliable identification of Fritillaria taxa during the vegetative stage or from vegetative fragments.