The anatomical and histochemical properties of endemic species Leiotulus aureus (Apiaceae)

Leiotulus aureus is an endemic umbellifer of the Balkan Peninsula and Turkey. It belongs to the rather complex tribe Tordylieae, whose genera are carpologically characterised in detail. However, information on the structure of its vegetative plant parts remains limited. Previous chemical research implies the presence of specialised structures related to the production of secondary metabolites. The aim of this study is the localisation of these anatomical features. The plant material was collected in Montenegro. The anatomy was studied using both paraffin sections and native sections stained with standard reagents for histochemical analysis, while fruit secretory products were characterised using Raman spectroscopy. Secretory structures were observed in all the plant parts of this monocarpic biennial or short-lived species, forming a network extending from the roots through the stem to the leaves, flowers and fruits. In the root, they are located exclusively in the cortical parenchyma, while in aboveground vegetative organs, they are found in the cortical parenchyma, in the ribs, aligned with vascular bundles. The fruits contain well-developed dorsal lateral and commissural vittae, while the dorsal median vittae and ducts associated with the vascular bundles are filiform and hardly recognisable. The presence of phenolic compound, flavonoids, fatty acids, and octyl-esters confirmed by histochemical staining, epifluorescence, Raman spectroscopy implies potential phytopharmaceutical properties and warrants further investigations of secondary metabolite pathways.