Plants annual or perennial. Stems 4-16 dm, densely to sparingly prickly. Leaf blades: surfaces copiously prickly on veins and intervein surfaces to sparingly prickly on main veins only; basal lobed ca. 1/2 distance to midrib, lobe apices usually distinctly rounded, marginal teeth usually less than 1 mm; distal usually definitely clasping. Inflorescences: buds oblong to ellipsoid to obovoid, body 12-22 × 10-16 mm, prickly; sepal horns terete, flattened or angular in cross section, (4-)6-8(-10) mm, unarmed to densely prickly. Flowers 5-10(-13) cm broad, not closely subtended by foliaceous bracts; petals white; stamens 150-250; filaments pale yellow; pistil 3-5-carpellate. Capsules ovoid, ellipsoid, or lanceoloid, 35-55 × 9-15(-18) mm (including stigma and excluding prickles), prickly, longest prickles to 10 mm, widely spaced, or shorter, more numerous, and interspersed with still shorter prickles, surface then partially obscured. Seeds 1.8-2.6 mm.
Ariz., Calif., Idaho, Nev., Oreg., Utah
Subspecies 4 (4 in the flora).
The Kawaiisu used Argemone munita medicinally to treat burns (D. E. Moerman 1986, no varieties specified).
|1||Prickles 0–30 per cm² on main stem below capsule; leaf surfaces unarmed or sparingly prickly on veins and intervein areas.||> 2|
|1||Prickles 100–500 per cm² on main stem below capsule; leaf surfaces mostly closely prickly on veins and intervein areas.||> 3|
|2||Prickles 0–10 per cm²; abaxial leaf surface sparingly prickly on main veins, adaxial surface usually unarmed.||Argemone munita subsp. robusta|
|2||Prickles 10–30 per cm²; both leaf surfaces sparingly to moderately prickly on veins and often on intervein areas.||Argemone munita subsp. munita|
|3||Longest prickles of stem 4–6 mm; stems usually purplish; bud prickles sometimes branched.||Argemone munita subsp. rotundata|
|3||Longest prickles of stem 7–10 mm; stems greenish white; bud prickles simple.||Argemone munita subsp. argentea|