On the floristic diversity of the floras of some geographic districts of the Tver oblast

The species composition of the regional floras of the Tver oblast is defined. Some of the geographic districts under study have landscapes with carbonate outcrops. The article contains the floristic inventory of mosses and vascular species of the Rzhev-Staritsa, Tvertza and the Mstinsk geographic districts. The regional floras are described from the point of view of their specific botanic and geographic features.