Petasites hybridus (L.) G.Gaertn., B. Mey. & Scherb butterbur; pestilence wort Family: Asteraceae
type: herbaceous perennial; Invasive
plant in spring
Petasites hybridus is an alien species in the USA, cultivated and rarely escaping, but often spreading aggressively where it is established. The flowering scape emerges and flowers open before the leaves appear. Photos above are from May 1, 2005 east of Eagle River in Vilas County, Wisconsin. Leaves subsequently become very large, to a blade diameter of about 1 meter and total leaf length extending to about 1.5 meters above the ground. Annecdotal reports describe roots extending to 5 feet below the ground.