*Lactuca serriola L.

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