Argemone rotundata Rydberg, Bull. Torrey Bot. Club 29: 160. 1902; A. munita var. rotundata (Rydberg) Shinners

Stems usually purplish, 4-10 dm, with 120-500 prickles per cm² on main stem below capsule, longest prickles 4-6 mm. Leaf blades: surfaces usually densely prickly on veins and intervein areas. Inflorescences: bud prickles sometimes branched. Capsules usually densely prickly, surface partially obscured, prickles unequal, longest to 8 mm. 2 n = 28.

Flowering spring-fall; fruiting summer-fall. Open slopes and foothills, full sun; 1200-2500 m; Ariz., Calif., Idaho, Nev., Oreg., Utah.