Japanese Butterbur

Japanese Butterbur (Petasites japonicus)

Report

2022-06-09-10.21.44-Brittania-Beach-SSISC-scaled-e1728597364716

Management Strategy

Synonyms

Fuki
Japanese sweet coltsfoot
Giant butterbur

ID Characteristics

Japanese butterbur is a perennial herbaceous plant that grows 0.2 – 1.0 m tall. It is an ancient medicinal plant used to treat various health issues, although modern studies have found it contains compounds that may harm human health.

Flowers: Japanese butterbur is dioecious, with male and female flowers on separate plants. It produces a cone-shaped flowerhead with many whitish disk flowers.

Stems: Thick and succulent stems with bristly hairs. The petiole (leaf stem) grows directly from the plant’s rhizomes (roots).

Leaves: Large, round, and kidney-shaped. The leaves can grow up to 60 cm wide.

Seeds: This plant produces 5 – 10 ribbed, glabrous (hairy) seeds. They have a pappus (tuft of hair) of white, hairy bristles.

Roots: Rhizome root system.

Similar Species

Invasive:

Common burdock (Arctium spp.) has smaller, heart-shaped leaves.

Exotic:

Common (or purple) butterbur (Petasites hybridus) has pink to purple flowers and its leaves are smaller.

5382463-PPT-200x284 — William M. Ciesla, Forest Health Management

Habitat and Origin

Japanese butterbur is native to parts of temperate Asia, including Japan, South Korea, and China. It was likely brought to BC by Japanese immigrants nearly 100 years ago. It is found in several provinces in Canada, including BC, Alberta, Ontario and Quebec.

Japanese butterbur likes constant moisture, and grows well in partially shaded areas such as shady woodlands, moist ditches, and beside creeks or streams.

How it Spreads

Japanese butterbur spreads by rhizome fragmentation and by seed.

Rhizome fragments can break off and spread along waterways, infesting areas downstream. Japanese butterbur can also be spread by seed, although this is unlikely outside of its native range due to the need for both male and female plants present. This plant is also occasionally sold as a garden ornamental, contributing to its spread.

Impacts

Ecological:

Its huge leaves shade out and outcompete native plants.
Other species can’t grow beneath it, leaving bare soil that causes erosion.

Health:

Contains a compound called petasitenine, which is carcinogenic if consumed.

Stop the Spread

Japanese butterbur is found in the Sea to Sky region, but with a limited distribution. The goal is to eradicate this species from the region and to prevent new introduction.

Learn to identify Japanese butterbur: use the images on this profile page to learn how to identify Japanese butterbur.

What to do if you spot it: You can report any Japanese butterbur sighting by visiting our reporting page.

DO:

Regularly monitor properties for weed infestations.
Ensure soil and gravel are uncontaminated before transport.
Minimize soil disturbances (e.g., use grazing plants that prevent soil exposure from overgrazing), and use seed mixes with dense, early colonization (e.g., alfalfa or barley) to re-vegetate exposed soil and resist invasion.
Ensure invasive plants (particularly flowering heads or root fragments) are bagged or covered to prevent spread during transport to designated disposal sites (e.g., landfill).

DO NOT:

Unload, park or store equipment or vehicles in infested areas; remove plant material from any equipment, vehicles or clothing used in such areas and wash equipment and vehicles at designated cleaning sites before leaving infested areas.
Plant Japanese butterbur in a garden, no matter how well-contained its enclosure may seem.
Move soil that has been contaminated with Japanese butterbur.
Place Japanese butterbur in the compost!

Control

Mechanical

Hand-pulling small infestations can be effective, but will need to be repeated over several years to remove new sprouts.
Mowing may hinder its spread but will not eradicate infestations.

Chemical

Many herbicide treatments seem ineffective in controlling Japanese butterbur; options for Japanese butterbur control in Canada are limited.

We recommend that any herbicide application is carried out by a person holding a valid BC Pesticide Applicator Certificate. Before selecting and applying herbicides, you must review and follow herbicide labels and application rates; municipal, regional, provincial and federal laws and regulations; species-specific treatment recommendations, and site-specific goals and objectives.