This genus of very ornamental, bushy plants has 33-35 species, mainly from Eurasia, two species from North America. There are 21 species in the Central and northern Asia, mainly in the Caucasus but also in the Far East, Central Asia and Siberia. All species are very attractive garden subjects but not all are easy to grow. Cultivars of P. lactiflora Pall. (from the Russian Far East) have been grown in gardens for 100's of years.