To Genus Directories:
Distribution: Widespread in the tropics and some in temperate regions.
Economic Uses: As an ornamental in warmer regions and perennials gardens as well as a house plant and the source of many red dyes, including henna.
Defining Features of Interest: In North America, the introduction of some species from Eurasia has caused anoverabundance in moist, disturbed areas and wetlands.
Fossil Evidence:Fossils in the Eocene.