Butterbur (Petasites hybridus) also known as butterfly dock, has been documented in Oakland County. This species is not widespread throughout the state. It prefers moist soil in wetlands, floodplains, and riverbanks. This herbaceous plant can grow up to 6 feet tall and has heart shaped leaves. Most leaves have fine hairs on the underside and can be as large as 2 feet across. The flowers appear on a spike and are pink to purple with white fruits.
Have you seen this species? Report it to us or on the MISIN website or smartphone app! Please include a photo to help with ID verification.
Environmental effects
Butterbur spreads through rhizomes underground. This allows it to multiply quickly and shade out all vegetation below the large leaves. This greatly reduces biodiversity in the area. When butterbur is the most prominent species on a riverbank there is very little to no stabilization. Rhizome roots do not grow deep so the soil is not held in place as well.
Treatment
This is a relatively new species to the United States, so treatment methods are still being researched. There is a recommended non-chemical and a chemical method that are determined to be the best as of now.
NON-CHEMICAL CONTROL METHODS:
- Hand pulling: since the roots are not deep this is a potential treatment method. However, the entire root system needs to be removed otherwise it will resprout. Plan to recheck the site for a few years to ensure no new growth has appeared.
CHEMICAL CONTROL METHOD
- Foliar spraying: herbicide sprayed directly onto the leaves. This is effective for non-sensitive and high-density areas. Note: herbicide sprayed onto nearby unattended plants will also be impacted.
Resources
State of Michigan Species Profile
Vermont Invasive website has a lot of useful information about identification and treatment methods.