Characteristics of plant communities containing St. John’s wort (Hypericum perforatum L.) in the Saratov Region

Analysis of 28 plant communities containing Hypericum perforatum L. in five different biotope types has been performed in 17 districts of the Saratov Region. A total of 325 species from 197 genera of 52 vascular plant species have been recorded, with plants characteristic of forest-edge, steppe, and anthropogenic biotopes prevailing in most communities. It has been shown that H. perforatum at the southeastern boundary of its range behaves as an explerent species. The main factor limiting its growth in biotopes of a certain type is the degree of disturbance in the structure of corresponding communities rather than by their taxonomic composition.