Any of three genera (Echinacea, Ratibida, and Rudbeckia). They are weedy plants in the composite family, native to North America. Some species in each genus have reflexed ray flowers. The purple-flowered perennials E. angustifolia and E. purpurea are often cultivated as border plants; they have strong-smelling black roots and hairy stems. These two species, along with E. pallida, are used to prepare an herbal cold and flu remedy called echinacea. Ratibida species have yellow ray flowers and brownish disk flowers. Prairie coneflowers (Ratibida columnaris and R. pinnata) are grown in wildflower gardens. Rudbeckia species have yellow ray flowers and brown or black disk flowers. Black-eyed Susan (Rudbeckia hirta), thimble-flower (R. bicolor), and cutleaf coneflower (R. laciniata) are grown as border plants.