The Polemoniaceae (jacob's ladder family or phlox family) comprises 18-25 genera with between 270-400 species of mostly annual plants, native to the Northern Hemisphere and also South America, with the center of diversity in western North America, especially in California. Only one genus (Polemonium) is found in Europe, and two (Phlox and Polemonium) in Asia, where they are confined to cool temperate to arctic regions; both genera also occur more widely in North America, suggesting relatively...
