About 33-35 species, mainly in Eurasia, two in North America. There are 21 species in the FSU, mainly in the Caucasus but also in the Far East, Central Asia and Siberia. All species are very attractive. Cultivars of P. lactiflora Pall. (Russian Far East) have been well-known in gardens for many centuries.
There are two other species with yellow flowers, unknown in cultivation, both native to the Caucasus.
Russian botanists accept also some other Caucasian species, such as red-flowered once: P. biebersteiniana Rupr., P. carthalinica Ketsk., P. majko Ketsk. and P. ruprechtiana Kem.-Nath., also pink-flowered P. lagodechiana Kem.-Nath. Some of these species are probably of hybrid origin. All are of horticultural value. P. cartalinica, with bright red flowers and leaves with narrow linear lobes closed very much to P. tenuifolia; and P. majko, with large, red flowers and bi-triternate leaves are especially attractive. Both occur in Georgia.