History and Introduction

Japanese butterbur, or fuki, is a perennial rhizomatous plant in the aster family native to Japan, China, and Korea that grows best in shaded, wet areas. It was first introduced to North America in the early 1900s in British Columbia as a garden crop for its rhubarb-like stems. Butterbur is traditionally pre-treated with ash or baking soda to reduce astringency, and made into soups, relishes, tempura, and more. Without pre-treating the plant or when consumed in excess, it is considered toxic or carcinogenic. It has also traditionally been used to treat headaches, asthma, and other ailments. Fuki is present in folklore of the Ainu people, appearing in mythology and art as the home to Koroppokuru, or “people beneath the fuki”. 

Today, it is present in the Northeast, Midwest, Pacific Northwest, and parts of Canada where it may grow in monocultures, shading out native vegetation and leading to erosion after senescing.

Japanese butterbur is also known as: fuki, great butterbur, giant butterbur, and sweet-coltsfoot.

Identification

Japanese butterbur has distinct kidney shaped leaves with toothed margins that can grow to four feet wide. Leaves are rough on the surface and sometimes hairy beneath. One leaf grows on each stem that sprouts directly from the plants’ rhizomes. The thick, bristly stems can reach up to four feet high. 

Its flowering stem will emerge prior to foliage in the spring, bearing compound white flowers on a compact, round flower head. Flower stems reach a maximum of one and one half feet in height, with male and female flowers growing on separate plants. Flower stems have narrow leaf-like bracts that alternate on the stalk and have parallel leaf venation. Butterbur flowers yield achenes, or small, dry, one-seeded fruits. 

Look-alikes

Common butterbur (Petasites hybridus): this butterbur is native to Europe, and its leaves may have been used to wrap butter, granting its common name. It is similar in appearance to Japanese butterbur, but bears dense spikes of pink flowers rather than white rounded umbel-like heads. Its leaves are also slightly smaller than Japanese butterbur, stretching only one to two feet across. This plant is known to be invasive in Michigan, Vermont, and other locations, but its distribution and invasiveness in our region are unknown.

Common burdock (Arctium minus): though also in the aster family, common burdock may only resemble butterburs in leaf morphology. Burdock plants possess broad, vaguely heart-shaped leaves that form short, dense rosettes in their first year and bolts taller in height in their second. The leaves of burdock are generally more elongated and smaller than those of butterbur. As burdock’s tall flowering stems rise to reveal spiked purple flower heads, the resemblance diminishes. 

Wild ginger (Asarum canadense): on first glance, wild ginger resembles a miniature version of butterbur and also represents a native alternative to its invasive counterpart. Its small heart-shaped leaves are paired with bright red flowers in early spring. Like butterbur, wild ginger prefers moist, shady environments. 

Colt’s foot leaves also resemble those of butterbur, but are smaller at only three to seven inches wide.

Damage and Concern

Butterbur threatens riparian habitats and disturbed sites, including roadsides, ditches, creek and streambanks, woodlands, and other moist areas. Its broad leaves shade out competing native vegetation, and rapidly creates a monoculture with its dense rhizomatous spread. When leaves die back all at once in autumn, the area may become vulnerable to erosion, especially on slopes and near moving water. 

It spreads by rhizome fragment, so care must be taken during manual removal, especially near moving water that could transport fragments and lead to the establishment of new populations. Butterbur can spread by seed, but its distribution within LIISMA is thought to be primarily due to intentional plantings at this time.

Management

Prevention is the best method of preventing the impact of invasive species. Avoid planting butterbur and choose native or non-invasive alternatives instead.

Manual or Mechanical Control: Digging to remove butterbur can be effective with care taken to remove as much of the rhizome as possible. Moist conditions may be most conducive to manual removal. Monitoring and repeated treatments will likely be necessary throughout the growing season and in following years. Take care to collect all rhizome fragments to prevent new plants from propagating. All materials should be bagged, tied up, and disposed of. Do not compost butterbur.

Chemical Control: Chemical treatment seems to be ineffective against butterbur. Little information is available regarding chemical treatment trials on this species. Chemical treatment trials may be necessary to determine best management practices for chemical control of butterbur. Chemical treatment on related species such as Petasites hybridus and Petasites alba may be useful in determining best management practices, which can be controlled with foliar applications of varying formulations.

For those seeking to control butterbur chemically, a FIFRA 2ee may be necessary in NYS to get permission to use an herbicide for perennial broadleaf plants to treat it. If the plant is growing nearby a stream or wetland (<100 ft), an aquatic formulation is likely necessary for most application methods to minimize negative impacts on aquatic life. Always follow the label instructions and apply accordingly. 

Reporting

LIISMA is currently monitoring butterbur to contain existing populations and prevent its spread to new areas. As reports of the species are collected, LIISMA is working with partners to delineate and manage small populations before they become widespread. Butterbur is currently a Tier 3 species within LIISMA, prioritized for containment.

Your reports matter to us – please report the species to iMapinvasives or iNaturalist as soon as you detect it.BBJap