Parthenium is a genus of North American shrubs in the sunflower tribe within the daisy family. The name Parthenium is derived from either the Greek word παρθένος (parthenos), meaning "virgin," or παρθένιον (parthenion), an ancient name for a plant. Members of the genus are commonly known as feverfew. Notable species include guayule (P. argentatum) which has been used as a rubber substitute, especially during the Second World War; and also P. hysterophorus, a serious invasive species in the Old World.