Prickly Lettuce, Compass Plant, Milk Thistle
Introduced biennial forb to 1-2m tall. Prickly or smooth stems. Leaf margins and midrib spiny. Leaves alternating up the stems, 3-20cm long, to 60mm wide, flat, glaucous, hairless, margins lobed, rarely entire. Upper leaves with basal lobes, stem-clasping. Flowers yellow, with 7-18 'petals’. Flower heads narrow cylindrical, forming a large open group at the top of the stem.
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 pages 718-719