 "Aster" species are used as food plants by the larvae of a number of Lepidoptera species—see list of Lepidoptera that feed on "Aster".Asters can grow in all hardiness zones.The genus "Aster" once contained nearly 600 species in Eurasia and North America, but after morphologic and molecular research on the genus during the 1990s, it was decided that the North American species are better treated in a series of other related genera.