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.)
Fig. 372. - Common Sow Thistle (Sonchus oleraceus). X 1/4.
Fig. 373. - Spiny-leaved Sow Thistle (Sonchus asper).
Means of control the same as for Common Sow Thistle.