Erect annual herb to 1.3 m high; stems branching, hispid. Leaves sessile or shortly petiolate, ovate, oblong or obovate, 1–12.5 cm long, 10–30 mm wide, pilose, gland-dotted; margin shallowly toothed to coarsely dentate. Capitula ± sessile, 1–2 cm diam.; outer involucral bracts elliptic, 4–7 mm long; inner involucral bracts spinescent at maturity, 5–9, initially olive-green or brown, with broad multicellular hairs along margin;ray florets 5–9; ligule c. 1.5 mm long; disc florets 5–7. Cypselas black, enclosed within swollen involucral bracts; entire accessory fruit compressed, cuneate, 4–7 mm long, with uncinate prickles and 2 divergent terminal spines; terminal spines 4–5 mm long. Flowers summer–autumn.
EGL. Also naturalised WA, NT, Qld, NSW. Native to South America. Found in Victoria in 2005 at Maffra in Gippsland, where it had spread from a batch of peanut straw brought from Queensland where the weed is more widespread and common.
