flat-bud prickly poppy

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. The Kawaiisu used Argemone munita medicinally to treat burns (D. E. Moerman 1986, no varieties specified).