12. Lactuca serriola Linnaeus, Cent. Pl. 2: 29. 1756.
野莴苣 ye wo ju
Lactuca altaica Fischer & C. A. Meyer; L. scariola Linnaeus.
Herbs 50-80 cm tall, annual. Stem solitary, pale, erect, usually branched only apically, glabrous or prickly setose in basal part. Leaves rather rigid, usually held in vertical plane in sunshine, midrib abaxially often prickly setose. Lower and middle stem leaves oblanceolate to narrowly elliptic, 3-7.5 × 1-4.5 cm, pinnatifid, pinnatisect, or more rarely not divided and leaf broadly linear, base auriculately clasping, margin spinulose; lateral lobes usually 3-6 pairs, truncate, falcate, triangular-falcate, or ovate-falcate; terminal lobe triangular-ovate, rhombic, or broadly linear. Uppermost stem leaves smaller, otherwise similar to middle stem leaves or lanceolate, linear-lanceolate, or linear, margin entire. Synflorescence paniculiform and much branched to almost racemiform in meager plants, with numerous capitula. Capitula with 15-25 florets. Involucre narrowly cylindric and 8-10 mm at anthesis, ovoid and ca. 6 mm in diam. in fruit. Phyllaries usually reflexed in fruit, apex acute; outer phyllaries ovate to lanceolate, approaching inner phyllaries in length; inner phyllaries ca. 8. Florets yellow. Achene body pale brown, narrowly obovoid, ca. 3.5 mm, compressed, with 7-9 ribs on either side; beak whitish, filiform, 3.5-5 mm. Pappus ca. 5 mm, ± caducous. Fl. and fr. Jun-Aug. 2n = 18.
Wastelands, roadsides, gravel areas on floodplains, rock crevices, grasslands on mountain slopes, mountain valleys; 500-2000 m. Taiwan (introduced), Xinjiang [Afghanistan, N India, Kashmir, Kazakhstan, Kyrgyzstan, Mongolia, W Russia, Tajikistan; N and NE Africa, SW Asia, Europe].
Because molecular analyses supported the earlier assumptions on morphological grounds that Lactuca altaica cannot be delimited from L. serriola they are treated as conspecific.
Lactuca serriola was first recorded in Taiwan in 2007 (C. M. Wang & C. H. Chen, Taiwania 55: 331-333. 2010) and seems to be naturalized there. It has also been introduced to S Africa, NE Asia, Australia, North America, Pacific islands (New Zealand), the Russian Far East, and S South America.