The park is home to 1400 species of vascular plants, or 38.88% of Bulgaria's total diversity. The highest number of species is concentrated in the coniferous and subalpine zones. The highest concentration of species is found in the Rila Monastery Forest Reserve, the valleys of the rivers Iliyna and Radovichka, and at the foothills of Kalin peak. The least diverse zone is the Alpine, with 250-300 species. There are five florogeographic components - Eurasian (158 species), Cirqumboreal (135 species, including glacial relicts), Central European (125 species), Mediterranean (307 species) and endemic (123 species, including 6 local, 27 Bulgarian and 90 Balkan endemic species). The most common local endemics are Rila primrose (Primula deorum) and Rila oak (Quercus protoroburoides), and from the Bulgarian ones - Jasione bulgarica, Alopecurus riloensis, Silene velenovskyana and Rila violet (Viola orbelica). Balkan endemic species include Bulgarian avens (Geum bulgaricum), yellow mountain lily (Lilium jankae), Fritillaria gussichiae, etc. The number of relict species is 110, or 7.86% of the park's vascular flora, including 77 glacial and 33 Tertiary relicts. 96 species are registered in the Red Book of Bulgaria and 14 are included in the IUCN Red List.