Sonchus sibiricus Linnaeus, Sp. Pl. 2: 795. 1753; Lagedium sibiricum (Linnaeus) Soják; Mulgedium kamtschaticum Ledebour; M. sibiricum (Linnaeus) Lessing.

Herbs 50-100 cm tall, perennial, with a taproot. Stem usually pale purplish red, erect, branched apically, glabrous, regularly leafy. Leaves thin, glabrous, abaxially glaucous green, adaxially green. Lower and middle stem leaves sessile, lanceolate, narrowly elliptic-lanceolate, or narrowly oblong-lanceolate, 10-26 × 2-3 cm, undivided or more rarely sinuate-dentate to pinnately lobed, base attenuate, auriculately or sagittately clasping, margin entire to faintly denticulate, apex acute to acuminate. Upper stem leaves similar to middle stem leaves but smaller. Synflorescence corymbiform to corymbosely paniculiform, with many capitula. Capitula with ca. 20 florets. Involucre cylindric, 0.9-1.3 cm. Phyllaries often purplish tinged or mottled; outer phyllaries triangular-ovate to lanceolate, apex acute; inner phyllaries ca. 8, apex subobtuse. Florets blue, rarely white. Achene brown to olive green, narrowly ellipsoid, ca. 4 mm, subcompressed, either marginal rib almost as thick as ca. 1/3 of achene diam., middle third with 4 or 5 narrow ribs on either side, apically attenuate or with a ca. 1 mm beak. Pappus 5-7 mm. Fl. and fr. Jul-Sep. 2n = 18*.

Forests, forest margins, meadows, riverbanks, moist places, by lakes; 300-2100 m. Gansu, Hebei, Heilongjiang, Jilin, Liaoning, Nei Mongol, Qinghai, Shaanxi, Shanxi, Xinjiang [Japan, Kazakhstan, Korea, Mongolia, Russia; N and NE Europe].