Lactuca sororia Miq., Ann. Mus. Bot. Lugduno-Batavum 2: 189. 1866; Hayata, J. Coll. Sci. Univ. Imp. Univ. Tokyo 18(8): 36. 1904; Icon. Pl. Formosan. 8: 75, figs. 31-35. 1919; Kitamura, Mem. Coll. Sci. Kyoto Imp. Univ., Ser. B, Biol. 23: 143. 1956; Li, Fl. Taiwan 4: 896. 1978.
Ixeris sororia (Miq.) Nakai, Bot. Mag. (Tokyo) 34: 155. 1922.
Perennials; stems (30-) 60-180 cm tall, erect, paniculately branched apically. Petiole 2.5-7 cm long, winged near blade or not winged. Lower cauline leaves thin, long petiolate, 12-23×5-10 cm, irregularly lyrate-pinnatisect to ovate-triangular, margins irregularly incised-lobed, distinctly mucro-nulate, upper surface crisp puberulous, loser surface glabrous; upper cauline leaves few, oblong to lanceolate, sessile, margins incised to mucronulate. Inflorescence paniculate, with minute lanceolate bracts, bracts 2-3 mm long; peduncle 8-24 mm long, few bracteolate, glabrous. Heads nodding in bud. Involucre cylindric, 8-9×2.5 mm, bracts glabrous, purple, outer ones much shorter, 2- or 3-seriate, ovate-oblong to oblong-lanceolate, 1-4 mm long, inner bracts 8, in 1 series, narrowly oblong. Florets 7-9; purple, 9-10×1-1.3 mm. Achenes linear-fusiform, 3.5-4×0.8 mm, black, 12-ribbed, beak 0.5 mm long. Pappus white, 7 mm long. Chromosome number, 2n = 18 (Peng & Hsu, 1978).
TAIPE: Shihting, Peng 6774. ILAN: Tahsi, Liao 325; Tsueifeng Lake to Tayuanshan, Peng 10339. TAOYUAN: Paling to Lalashan, Peng 11028. HSINCHU: Wufeng, Peng 9381; Yuanyanghu, Chen 163. MIAOLI: Shihtan, Peng 15055. TAICHUNG: Wushihkeng, Yang 6790; Wuling Farm, Peng 8011. NANTOU: Meifeng, Peng 1080; Huishun Forest Area, Peng 14027. PINGTUNG: Wutoushan, Wang 1023. HUALIEN: Huangma to Walami, Liao 1572; Tatung to Chingshuishan, Ho 1234.
Korea, Japan, Vietnam and China. Taiwan, semishaded habitats from low to mid elevations.
