The Polemoniaceae are a family (Jacob's-ladder or phlox family) of about 25 genera with 270-400 species of annual and perennial plants, native to the Northern Hemisphere and 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 recent colonization of the Old World from North America.