(n)European hawkweed having flower heads with bright orange-red rays; a troublesome weed especially as naturalized in northeastern North America; sometimes placed in genus Hieracium, Syn.Hieracium aurantiacum, Pilosella aurantiaca
n. (Bot.) (a) A plant of the genus Hieracium; -- so called from the ancient belief that birds of prey used its juice to strengthen their vision. (b) A plant of the genus Senecio (Senecio hieracifolius). Loudon. [ 1913 Webster ]