Description from Flora of China
Brachyramphus sinicus Miquel; Lactuca amurensis Regel & Maximowicz ex Regel; L. brevirostris Champion ex Bentham; L. cavaleriei H. Léveillé; L. indica f. indivisa (Maximowicz) H. Hara; L. indica f. runcinata (Maximowicz) Kitamura; L. kouyangensis H. Léveillé; L. laciniata (Houttuyn) Makino (1903), not Roth (1797); L. squarrosa (Thunberg) Miquel; L. squarrosa var. dentata Komarov; L. squarrosa f. indivisa Maximowicz; L. squarrosa var. integrifolia Komarov; L. squarrosa var. laciniata (Houttuyn) Kuntze; L. squarrosa f. runcinata Maximowicz; L. squarrosa var. runcinatopinnatifida Komarov; Prenanthes laciniata Houttuyn; P. squarrosa Thunberg; Pterocypsela indica (Linnaeus) C. Shih; P. laciniata (Houttuyn) C. Shih.
Herbs 0.4-2 m tall, annual or perennial. Roots narrowly thickened. Stem solitary, stout, erect, branched apically, glabrous. Lower and middle stem leaves 13-37 × 0.5-20 cm, glabrous, base semiamplexicaul to weakly amplexicaul, margin entire or sparsely dentate, apex obtuse to acuminate; shape and incision extremely variable; shape ranging from linear-lanceolate, linear-elliptic, lanceolate, spatulate, to elliptic; incision ranging from entire, pinnatifid, deeply pinnatifid, to bipinnatifid, with segments mostly narrow, linear, falcate, triangular-lanceolate, or elliptic, apex acute to acuminate. Upper leaves smaller, linear-lanceolate, linear, or elliptic, less incised to entire. Synflorescence paniculiform to racemiform-paniculiform, with numerous capitula. Capitula with usually 20-30 florets. Involucre cylindric, 1-1.1 cm at anthesis, 1.2-1.5 × 0.6-0.8 cm in fruit. Phyllaries usually with a purplish margin, apex usually obtuse to rounded; outer phyllaries ovate to lanceolate, longest ca. 6 × 1.5-2 mm; inner phyllaries 8. Florets pale yellow, bluish purple on drying. Achene 3-5 mm; body reddish brown, dark brown, or blackish brown, ellipsoid, compressed, broadly winged, 1.2-2.5 mm wide, with 1 prominent rib on either side, apically contracted into an apically pale to greenish subfiliform 0.4-1.6 mm beak. Pappus 7-8 mm, caducous. Fl. and fr. Apr-Nov. 2n = 18*.
Lactuca indica is one of the commonest species of tribe Cichorieae in China. Leaf shape shows a similarly strong variation as that in L. raddeana and is in a quite similar way ± continuous. Leaf shape is therefore not suitable for species delimitation in this group of species. In China, L. indica also shows considerable variation in achene beak length; therefore, the differences with L. formosana are sometimes not so clear-cut. See note under the latter species.
Mountain valleys, forests, forest margins, thickets, ravines, grasslands, fields, wastelands; 200-3000 m. Anhui, Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hebei, Heilongjiang, Henan, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Xizang, Yunnan, Zhejiang [Bhutan, India, Indonesia, Japan, Korea, Philippines, E Russia, Thailand, Vietnam; introduced elsewhere].