Japanese coltsfoot
Petasites japonicus
Family: Asteraceae
Other Scientific Names:
Nardosmia japonica
Other Common Names: Japanese sweet coltsfoot, giant butterbur, fuki, Japanese butterbur
Weed class: monitor list
Native to: Native to parts of temperate Asia - eastern Russian Federation, China, Japan, and South Korea
Why Is It a Noxious Weed?
This plant is on the monitor list - it is not a listed noxious weed in Washington. Please contact its sponsor Patricia Grover via noxiousweeds@agr.wa.govto report locations of plants growing outside of ornamental plantings.
How would I identify it?
General Description
A perennial herbaceous plant with creeping rhizomes that sends up flowering stems first, followed by large, rounded basal leaves on long stalks (petioles).
Flower Description
Flower stalks grow from rhizome, up to 1.5 feet tall, with many flowerheads of whitish disk flowers. Plants in the Petasites genus are typically dioecious, with male and female flowers on separate plants.
Leaf description
Basal leaves with long petioles grow directly from the rhizomes. Leaf blades rounded to round-kidney shaped, ranging in width up to 5 feet (1.5 m) wide for the variety giganteus. Blades have toothed margins and are sometimes quite hairy on undersides (white-woolly) or almost hairless, while upper leaf surface is green with some hairs. Flower stems have alternate, leaf-like bracts that are narrow and have parallel veins.
Fruit Seed Description
Achenes (a small, dry one-seeded fruit), about 3.5 mm long, hairless, with 5 to 10 ribs on surface, with a tuft of bristles about 12 mm long on its end.
Where does it grow?
Roadsides, ditches, along creeks and streams, woodlands, wet areas - on moist ground.
For More Information
E-Flora BC: Electronic Atlas of the Flora of British Columbia
UW Herbarium Image Database Information
Information from WeedWise Clackamas SWCD
Additional Photos
