Nardosmia japonica Siebold & Zuccarini, Fl. Jap. 181. 1843; Petasites albus A. Gray (1857), not Linnaeus (1753); P. liukiuensis Kitamura; P. spurius Miquel; Tussilago petasites Thunberg.

Rhizomes creeping, with subterranean procumbent branches, with membranous ovate scales, and numerous fibrous roots. Stems 15-30 cm tall, basally 7-10 mm in diam., simple, densely or laxly shortly brown pubescent. Basal leaves long petiolate; blade adaxially green, orbicular or reniform-orbicular, 15-30 × 15-30 cm, papery, abaxially arachnoid, later glabrescent, adaxially crisped-pubescent when young, base cordate, margin finely toothed. Bracteal leaves oblong or ovate-oblong, 3-8 cm, parallel veined, apically obtuse. Male scapes with numerous capitula (20-30) crowded in a terminal corymb, homogamous; involucres tubular, ca. 6 × 7-8(-10) mm, base with lanceolate bracts; phyllaries biseriate, subequal, narrowly oblong, glabrous, apically obtuse; all florets tubular, functionally male; corolla white, 7-7.5 mm, tube ca. 4.5 mm; anthers basally obtuse; style clavately thickened with small ring below stigma, apex 2-fid. Female scape 15-20 cm tall, densely bracteate, often elongated after anthesis, ca. 70 cm tall, in dense corymbs, rarely branched; capitula homogamous; florets numerous, corolla filiform, ca. 6.5 mm, apex obliquely truncate; stigma distinctly exserted from corolla, capitate, 2-fid, papillose. Achenes cylindric, ca. 3.5 mm, glabrous. Pappus of many fine bristles, white, ca. 12 mm. Fl. Apr-May, fr. Jun.

The rhizomes of Petasites japonicus are used medicinally for treating injuries, trauma, swelling, and fractures, and for detoxification of snakebites. The stalk is cultivated as a vegetable, and the young immature capitula are delicious.

Streamsides, grasslands, thickets. Anhui, Fujian, Henan, Hubei, Jiangsu, Jiangxi, Shaanxi, Shandong, Sichuan, Zhejiang [Japan, Korea, Russia (Far East)].