25 to 60 species, depending on classification. In subtropical regions of Europe, America, Asia and Australia. 8 species in the FSU, mainly in Central Asia, also in southern Russia and southern Siberia.
Also adapted to extreme conditions are the following species unknown in cultivation:
They also differ in distribution areas, and vary in inflorescence structure (axillary or terminal), flower colour (white, pink) etc. All species can grow in areas belonging to USDA zones 6 or 5. F. tuvinica grows in zone 4.