fleabane, any plant of the genus Erigeron, widely distributed herbs of the family Asteraceae (aster family), especially abundant in temperate and mountainous regions of North America. The flowers, ranging from white to pink and purple, resemble daisies or asters, hence many of the common names, e.g., the daisy fleabanes (E. ramosus, strigosus, and sometimes other species), widespread weeds, and the beach aster, or seaside daisy (E. glaucus), of the Pacific coast. The eastern E. pulchellus is called robin's-plantain. Other similar composites are sometimes also called fleabane. Fleabane is classified in the division Magnoliophyta, class Magnoliopsida, order Asterales, family Asteraceae.