4. Eupatorium formosanum Hayata, J. Coll. Sci. Imp. Univ. Tokyo. 25(19): 122. 1908.
台湾泽兰 tai wan ze lan
Eupatorium cannabinum Linnaeus subsp. asiaticum Kitamura; E. formosanum var. quasitripartitum (Hayata) Kitamura; E. quasitripartitum Hayata.
Herbs, perennial, ca. 2 m tall. Stems erect, fascicled; branches obliquely ascending, divaricate synflorescence branches corymbose, slender; stems and branches green initially, densely ferruginous puberulent, later glabrescent, gray-brown. Leaves opposite; median stem leaves 3-partite; central lobe lanceolate, large, 10-15 × 2.5-3 cm, base cuneate, apex acuminate; lateral lobes lanceolate, small; upper leaves gradually smaller; lower leaves simple, ovate or broadly ovate; upper leaves abaxially pale green, adaxially green, narrowly ovate or ovate-lanceolate, abaxially with many yellow glands and densely adpressed puberulent, adaxially sparsely scabrid-hairy, pinnately veined, lateral veins 5-7-paired, adaxially slightly prominent. Synflorescence of lax terminal corymbs 8-11 cm in diam. Capitula numerous, 5-flowered; involucre campanulate, ca. 5 mm; phyllaries 3-seriate, imbricate, outer phyllaries elliptic, 1-1.5 mm, median and inner phyllaries longer, narrowly elliptic, ca. 5 mm, all phyllaries obtuse, glabrous and eglandular; corollas white, ca. 3.5 mm. Achenes black-brown, ca. 2.5 mm, angled, without hairs and glands; pappus off-white, ca. 3 mm. Fl. and fr. Dec-Aug. 2n = 20*.
Forest margins, grasslands. Taiwan [Japan (Ryukyu Islands)].