The aim of the work was to determine the species composition of woody and shrubby plants of the State Natural Park “Medeu” and to identify invasive species. For the first time, an assessment of the aggressiveness of invasive species and their impact on the ecosystem was carried out. The article provides an analysis of the dendroflora of the GRPP “Medeu”. The species composition of native and invasive species was revealed, the degree of aggressiveness of the latter and the peculiarities of their distribution were analyzed using the species abundance assessment scale. It is shown that the uncontrolled spread by self-seeding and overgrowth of particularly aggressive plant species such as Acer campestre, Acer negundo, Fraxinus excelsior has a depressing effect on the local natural flora, leads to the homogenization of ecosystems and a decrease in the biodiversity of cenoses, by reducing the number of individual species and reducing their ranges. This may further lead to the complete destruction of wild fruit forests growing in this region, and disruption of the ecosystem of plant communities in which red Book plants grow. During the survey conducted on the territory of the Medeu State Regional Natural Park were identified 35 naturally growing species of trees and shrubs 5 of which are red-listed, 27 alien species, three of which are classified as aggressive, and 13 invasive species that may eventually become aggressive.