Vascular Plants of Wisconsin

Petasites hybridus (L.) G.Gaertn., B. Mey. & Scherb
butterbur; pestilence wort
Family: Asteraceae

native: no
type: herbaceous perennial; Invasive

flowers leaf flowers flowering scape
plant in spring early leaf flowers flowering scape

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.

known distribution based on vouchers


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