Sparingly branched annual with stems to c. 60 cm tall, densely covered with subulate yellow prickles and stellate hairs. Petioles to 7 cm long. Lamina to c. 10 × 5 cm, ± ovate, with scattered prickles, stellate-hairy, densely so below, deeply 1-2-pinnatisect with lobes rounded at the sinuses and apices; base cuneate to attenuate, sometimes asymmetric. Cymes with several fls racemosely arranged, densely prickly; peduncles to c. 8 cm long at anthesis; pedicels short, spreading. Calyx 5-7 mm long, densely prickly with surface often obscured, stellate-tomentose, accrescent; lobes linear-lanceolate. Corolla 2-2.8 cm diam., yellow, densely stellate-hairy outside; lobes ovate. Shorter anthers c. 6 mm long; larger lower anther c. 10 mm long, with incurved beak. Berry c. 1 cm diam., globose, red, loosely enveloped in the enlarged, prickly calyx and thus fr. burr-like; stone cells probably 0. Seed 2-3 mm diam., very irregular in shape.