Description from Flora of China
Eupatorium chinense var. oppositifolium (Koidzumi) Murata & H. Koyama; E. chinense var. yuliense C. H. Ou; E. crenatifolium Handel-Mazzetti; E. makinoi T. Kawahara & Yahara; E. makinoi var. oppositifolium (Koidzumi) T. Kawahara & Yahara; ?E. melanadenium Hance; E. sachalinense Makino var. oppositifolium Koidzumi.
Herbs, perennial, or small shrubs or subshrubs, (50-)70-100(-250) cm tall. Lower part woody, well branched, stems often purplish red; branches ascending, upper branches and corymb sordid-white puberulent, synflorescence branches and peduncles more densely hairy, glabrescent in lower part by anthesis. Leaves opposite, sessile or subsessile with petiole to 2-4 mm; median stem leaves simple or 3-lobed, ovate or broadly ovate, 4.5-10(-20) × (2-)3-5(-6.5) cm, both surfaces scabrid, white puberulent and glandular, more densely so abaxially and on veins, pinnately veined, veins 3-7-paired, base rounded, margin regularly crenate-serrate, apex acuminate or obtuse; upper stem leaves homomorphic with median leaves, but smaller; radical leaves withered by anthesis, margin irregularly crenate. Synflorescences terminal, of large laxly compound corymbs, 20-30 cm in diam. Capitula numerous, 5-flowered; involucre campanulate, ca. 5 mm; phyllaries 3-seriate, imbricate; outer phyllaries short, ovate or lanceolate-ovate, outside puberulent and sparsely glandular, 1-2 mm; median and inner longer, elliptic or elliptic-lanceolate, 5-6 mm, apically and marginally white, membranous, glabrous, but with yellow glands; corollas white, pink, red, or reddish purple, ca. 5 mm, with yellow glands. Achenes pale black-brown, elliptic, ca. 3 mm, 5-ribbed, yellow glandular; pappus setae white, ca. 5 mm. Fl. and fr. Jun-Nov. 2n = 20, 30, 31, 39, 40, 50.
One of us (Chen) does not accept the broad view of Eupatorium chinense by King and Robinson (Monogr. Syst. Bot. 22: 1-581. 1987), who included E. japonicum, together with many other synonyms, but excluded E. reevesii Wallich ex Candolle, which was synonymized with E. squamosum D. Don.
T. Kawahara et al. (Pl. Sp. Biol. 4: 37-46. 1989) found sexual diploids with restricted distribution and agamospermous polyploids with broad distributions in this complex. They mentioned sexual populations belong to different varieties, which are morphologically distinct from each other and have allopatric distributions, but agamospermous populations may be of hybrid origin and have significant morphological variation.
Eupatorium chinense is poisonous, especially the leaves, but it is used medicinally to treat large carbuncles, scabies, snakebites, and to alleviate pain.
Forest margins on slopes, forests, thickets or grasslands on slopes; 200-1900 m. Anhui, Fujian, Gansu, Guangdong, Guangxi, Guizhou, Hainan, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Sichuan, Taiwan, Yunnan, Zhejiang [India, Japan, Korea, Nepal].