Common Sowthistle, Milk Thistle
Introduced annual forb to 1.1m tall. Leaves alternating up the stems, occasionally clustered at the base of the plant. Leaves with pointed basal lobes, 6-35cm long, 30-120mm wide, flat, hairless, entire to lobed, the lobes toothed, and with soft spines, tips blunt or pointed. Flowers yellow, with many ‘petals’. Flower heads oval to top-shaped, in groups at the ends of the stems.
Differs from Sonchus asper in that the leaves are thin and soft, and dull green.
Differs from Sonchus hydrophilus in that the edges of the leaves are spiny.
Description and photo in G.M. Cunningham, WE Mulham, PL Milthorpe and J H Leigh (1981 and later printings) Plants of Western New South Wales page 718