Petasites japonicus (Siebold & Zucc.) Maxim.
Japanese butterbur (Japanese sweet coltsfoot)
Asteraceae (Aster family)

Introduction to Vascular Plants


© Adolf Ceska     (Photo ID #13608)


E-Flora BC Static Map

Distribution of Petasites japonicus
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Species Information

Perennial herb from a creeping rhizome; stems erect, branched above, numerous, sparsely long-hairy to thinly woolly-hairy, 0.2-1.0 m tall; flowering stems appear before the leaves.
Basal leaves arising directly from the rhizome, thick, round to heart-shaped on long stalks, shallowly to conspicuously toothed, usually with 20 or more teeth per side, white-woolly to nearly glabrous beneath, green and somewhat hairy above, the blades 20-40 cm long, 10-60 cm wide; stem leaves reduced to parallel-veined bracts, 1-8 cm long, reduced upwards, sparsely long-hairy.
Heads disciform in elongate to flat-topped clusters, stalks moderately to densely white-woolly; involucres 6-12 mm tall; involucral bracts lance-shaped with hairs at the base, green, sometimes with translucent margins; disk flowers whitish.
Achenes 5- to 10-ribbed, glabrous; pappus of white, hairlike bristles.

SourceThe Illustrated Flora of British Columbia


If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.

Habitat and Range

Moist ditches and fields in the lowland zone; infrequent in SW and SC BC; introduced from Japan.

SourceThe Illustrated Flora of British Columbia


Synonyms and Alternate Names:
Nardosmia japonica Siebold & Zucc.