‖n. [ NL. So named after Olaf Rudebeck, a Swedish botanist. ] (Bot.) A genus of composite plants, the coneflowers, consisting of perennial herbs with showy pedunculate heads, having a hemispherical involucre, sterile ray flowers, and a conical chaffy receptacle. There are about thirty species, exclusively North American. Rudbeckia hirta, the black-eyed Susan, is a common weed in meadows. [ Webster 1913 Suppl. ]