The tree and shrub flora of the Kaczawa Mountains (Sudetes, Poland) consists of 240 taxa, of which over 70 % are native. The biodiversity and chorological differentiation are reflected in a number of biogeographical phenomena, such as differences in floristic richness of native and alien species, concentration of borderline species, and co-occurrence of various taxa. Concentration maps of particular groups of taxa in the investigated area together with the statistical analysis point to distinct relationships between the distribution of these groups and earlier recognized phytogeographical units of the rank of three subdistricts (Kaczawa Mountains, Western Kaczawa Plateau, Eastern Kaczawa Plateau), which include eight geobotanical sections. The distinguished phytochorions cover territories of various areas demarcated by natural borders and characterized by specific components of woody flora, concentration of taxa exhibiting particular types of local geographical range, as well as by altitude, relief, geological structure, and local climatic and hydrological parameters.