Sonchus dsper, Hill trate the skin. Stems one to six feet high, smooth, angled, branching, full of milky sap. Lower leaves sometimes pinnatifid but usually undivided and spatulate, tapering to margined petioles; stem-leaves oblong or lance-shaped, clasping the stem with rounded auricles, the margins prickly-toothed, the surfaces dark green, smooth, and shining. Heads similar to those of the Common Sow Thistle. Achenes oblong, compressed, margined, with smooth ribs. (Fig. 373.)

Introduced. Annual. Propagates by seeds. Time of bloom: May to October. Seed-time: June to November. Range: All cultivated parts of the world. Habitat: Fields, roadsides, waste places.

More prickly than the preceding species; the spines, though weak compared with those of true thistles, can make themselves felt when touched, while those of the Hare's Lettuce are too soft to pene-

Fig. 372. - Common Sow Thistle (Sonchus oleraceus). X 1/4.

Fig. 373. - Spiny-leaved Sow Thistle (Sonchus asper).

X 1/4.

Means of control the same as for Common Sow Thistle.