Lactuca L.
Involucral bracts in 4–5 rows. Heads terminal or terminating branches. Cypselas flattened, ribbed longitudinally Lactuca
Cauline leaves linear-lanceolate, entire, glabrous, stem-clasping; basal leaves pinnatisect, with few lobes, up to 20 cm long. Heads subsessile in the leaf axils. Involucre 3 mm diam. Cypselas glabrous, black, 2–3 mm long, with a beak 3–5 mm long. Pappus hairs 3–4 mm long. Glabrous herb up to 1 m high. Widespread. Weed of cultivation, pastures and waste places. Introd. from Europe; Asia and Africa. Fl. summer. Willow-leaved Lettuce Lactuca saligna
Cauline leaves broad-oblong, pinnatifid; the longest up to 10 cm long, mostly twisted at the base so as to be vertical, spinulose on the margins and often on the midrib underneath; upper leaves stem-clasping. Heads in a terminal panicle. Involucre 3–4 mm diam. Cypselas grey, ciliate towards the summit, 3 mm long; the beak as long or longer. Pappus hairs 5 mm long. Herb up to 2 m high. Widespread. Weed of cultivation, pastures and waste places. Introd. from Europe; Central Asia. Fl. summer. Prickly Lettuce or Compass Plant Lactuca serriola