Abstract
The adventive fraction of the flora of Seymskiy Regional Landscape Park (Sumy Oblast, Ukraine) including 237 species of 183 genera and 62 families, is described. Its systematic and biomorphological structures was analyzed. The major families, namely Asteraceae, Poaceae, Brassicaceae, Fabaceae, Rosaceae, Lamiaceae, Boraginaceae, Chenopodiaceae, Solanaceae and Malvaceae are represented by 152 species (64.1% of the alien fraction). Therophytes (49.4%), hemicryptophytes (28.7%) and phanerophytes (17.7%) were found to be the prevailing life forms in the alien flora of the park. According to the time of immigration, kenophytes (69%) predominate among alien species of the park. The most common species belonged to the group native of North America (23.2%), the Mediterranean (21%), Asian (17.7%) and Mediterranean-Iran-Turanian (11.4%). Xenophytes (54.4%) predominated by way of penetration into the territory, ergasiophytes were represented by 39.6% and xeno-ergasiophytes by 5.9% of the species. According to the degree of naturalization epoecophytes (30%) and agrio-epoecophytes (27.8%) had high ranked positions as part of the alien flora and there are slightly less ephemerophytes (14.8%), colonophytes (14.3%), agriophytes (6.8%) and ergasiophygophytes (6.3%). At the time of the survey, we considered 162 species as naturalized, 50 taxa as casuals, 16 species as potentially invasive, and 9 as those of invasive status. The obtained data indicated the need for action to stop the increase in the adventive species within the park's flora in order to reduce their negative impact on natural habitats and the native flora.