Stems 6-15 dm, with 10-30 prickles per cm² on main stem below capsule. Leaf blades: surfaces sparingly to moderately prickly on veins and intervein areas. Capsules moderately prickly, surface not obscured, prickles uneven, longest 5-8 mm. 2 n = 28.

Flowering spring-summer; fruiting summer-fall. Dry foothills and slopes; 100-1500 m; Calif.; Mexico (Baja California).

Argemone munita subsp. munita grows in the Coast Ranges. Intermediates between it and subsp. rotundata are frequent.