Abstract
Tri ushi is a mountain Ridge located in the Western Stara Planina Mountains (Western Bulgaria). A study of medicinal plants of this part of the Stara Planina Mts is being done for the first time. During the research conducted in 2024 on the territory of the Tri ushi Mountain Ridge, we identified 209 species of medicinal plants, which belong to 161 genera and 51 families. This represents 24.73% of the species, 36.26% of the genera and 43.22% of the families of medicinal plants in Bulgaria. Among the life forms, the most widespread are hemicryptophytes (46.89%). Among the biological types, perennial herbaceous plants prevail (56.46%). The described medicinal plants belong to 30 floral elements. Two species of Balkan endemics and 19 relict species were identified, of which 18 species are Tertiary relicts and one species is a Quaternary relict. The species with conservation status are 14 in number (6.70%). Anthropophytes are 149 species (71.29%). On the territory of the Tri ushi Mountain Ridge, we identified 5 invasive alien plant species (2.39% of medicinal plants), one of which is among the most dangerous invasive alien species threatening biodiversity in Europe. Poisonous plants and species causing side effects upon physical contact with them or their components were identified. The results obtained were compared with the data on medicinal plants on the Chepan Mountain. Both territories are located within the boundaries of BG0000322 Dragoman - a protected area of the Natura 2000 European ecological network.