2. Sonchus wightianus Candolle, Prodr. 7: 187. 1838.
苣荬菜 ju mai cai
Sonchus lingianus C. Shih; S. picris H. Léveillé & Vaniot; S. wallichianus Candolle; S. wightianus subsp. wallichianus (Candolle) Boulos.
Herbs 30-150 cm tall, perennial, with a taproot. Stem branched from base or higher, glabrous below synflorescence. Basal and lower stem leaves oblanceolate to elliptic, 6-24 × 1.5-6 cm, undivided or pinnatifid to pinnatipartite, glabrous, base narrowed (in basal leaves) to auriculately clasping (in lower stem leaves), margin denticulate to mucronulately dentate, apex obtuse to acute; lateral lobes if present 2-5 pairs, lanceolate, ovate, semiorbicular, or sometimes triangular-ovate; terminal lobe narrowly ovate to elliptic, ± large, apex obtuse to acuminate. Middle and upper stem leaves elliptic to lanceolate, smaller, otherwise similar to lower leaves. Synflorescence corymbiform, with several to many capitula. Capitula with very many (usually 180-300) florets; peduncle slender, apically white tomentose, densely glandular hairy or non-glandular. Involucre broadly campanulate, 1.2-1.5 cm, base ± white villous to tomentulose and glandular hairy or not. Phyllaries with or without glandular hairs, apex long acuminate; outer phyllaries lanceolate, 1-1.5 mm wide. Corolla 1.2-1.4 cm. Achene narrowly ellipsoid, 3.5-4.5 mm, moderately compressed, ± elliptic in cross section, weakly rugose, between lateral ribs and with 1(or 2) weakly prominent main rib(s) and several secondary ribs on either face. Pappus 6-9 mm, ± persistent. Fl. and fr. Jan-Oct. 2n = 18.
Grasslands on mountain slopes, grasslands in forests, forest margins, thickets, beside fields, moist places or near water, wastelands on mountain slopes, gravelly areas by rivers; 300-2300 m. Fujian, Guangdong, Guangxi, Guizhou, Hainan, Hubei, Hunan, Jiangsu, Ningxia, Shaanxi, Sichuan, Taiwan, Xinjiang, Xizang, Yunnan, Zhejiang [NE Afghanistan, Bhutan, India, Indonesia (Java), Kashmir, Laos, Malaysia (Peninsular), Myanmar, Nepal, N Pakistan, N Philippines (Luzon), Sri Lanka, N Thailand, N Vietnam].
Sonchus wightianus has frequently been misidentified with the habitually similar S. arvensis, which is chiefly restricted to Europe (but also introduced to North America) and a hybridogenous species, in which a tetraploid (2n = 36) S. arvensis subsp. uliginosus (M. Bieberstein) Nyman (with non-glandular capitula and peduncles) and a hexaploid (2n = 54) S. arvensis subsp. arvensis (with glandular capitula and peduncles) are distinguished. Sonchus arvensis is probably derived from hybridization, in which S. brachyotus and/or S. wightianus on the maternal side and S. maritimus and/or S. crassifolius Pourret ex Willdenow on the paternal side are involved (S. C. Kim et al., Molec. Phylogen. Evol. 44: 576-597. 2007). The diploid S. wightianus has adaxially often reddish marginal florets and does not, in contrast to S. arvensis and S. brachyotus, produce shoot-bearing roots. Also, in S. wightianus plants with non-glandular or glandular peduncles and capitula occur. The former have been distinguished as S. wightianus subsp. wallichianus and referred to in FRPS (80(1): 66. 1997) as S. uliginosus (= S. arvensis subsp. uliginosus), but they seem to be neither geographically nor ecologically separated. Absence of glandular indumentum is a variation not uncommon in Sonchus, as in the case of S. wightianus, and apparently is without systematic value. Sonchus lingianus, described from China, is a mere form of S. wightianus with spatulate to narrowly elliptic, undivided leaves.