Typically Sonchus asper has glossy green leaves with many (soft) prickly tips, In rare cases, however, their color can also be blue-green, which is otherwise more typical for Sonchus oleraceus. In difficult cases the fruits provide unquestionable identification attributes: The achenes of Sonchus asper are more bulbous than the more elongated ones of Sonchus oleraceus. Beneath the longitudinal furrows which are availabe at both, the achenes of Sonchus oleraceus have usually a transversely wrinkled surface, which is not present on the achenes of Sonchus asper with smooth surface.