A detailed anatomical approach to taxonomically problematic endemic Seseli L. (Apiaceae) taxa in Türkiye

In this study, the vegetative anatomical features of the taxa, which were previously named as Seseli gummiferum subsp. ilgazense A.Duran, Ö.Çetin & M.Öztürk and S. paphlagonicum Pimenov & Kljuykov, were compared with a closely related species, S. resinosum Freyn & Sint., which is also endemic in Türkiye. The root, the stem, the leaf segment, the petiole, and the rachis parts were examined anatomically and explained in detail for the first time to discuss the results of recent morphological and molecular studies with the anatomy of the taxa. The results show that S. gummiferum subsp. ilgazense and S. paphlagonicum have anatomically similar characters. However, in terms of the same characters, these taxa quite differ from a closely related species, S. resinosum. The most prominent different characters can be listed as the shape of stems, petioles and rachis, the presence of sclereids in the roots, the collenchyma arrangement of stems and petioles, the surface view of rachis and the sclerenchyma above floem in the stems and rachis. This revisional and detailed descriptive study highlights the importance of anatomy in the taxonomy of Apiaceae, and it is obvious that it will assist future taxonomic research in the genus.