Plants annual or short-lived perennial. Stems branching distally, 3-10 dm, sparingly prickly. Leaf blades: abaxial surface sparingly prickly on veins, adaxial surface usually unarmed; proximal deeply lobed nearly to midrib; distal more shallowly lobed, usually clasping. Inflorescences: buds oblong, body 8-18 × 4-11 mm, with 4-10 prickles per sepal; sepal horns terete, 5-12 mm, unarmed. Flowers 3-7 cm broad, closely subtended by 1-2 foliaceous bracts; petals lemon yellow or rarely darker yellow; stamens 20-75; filaments yellow; pistil 3-6-carpellate. Capsules ovoid-ellipsoid to oblong, 20-50 × 10-18 mm (including stigma and excluding prickles), longest prickles 8-12 mm. Seeds 1.5-2 mm. 2 n = 56. Flowering and fruiting spring-fall. Disturbed soil, often a weed of fields, roadways, embankments, intermountain plains; 0-2250 m; introduced; Ariz.; Mexico. Argemone ochroleuca is widespread in temperate and tropical regions of the world as an introduced weed.

Plant: shrub or herb; STEMS with scattered, perpendicular or slightly declined prickles, 0-10 per square cm of surface, more abundant upward, the largest prickles 5-10 mm long Leaves: with scattered prickles on the veins below, 0-4 prickles per square cm, nearly or quite smooth above, lower and middle cauline leaves lobed three-fourths to five-sixths to the midrib, the lobes about 1-1.5 times as long as wide, mostly 3-5 on each side of the midrib, about equaling the sinuses in width; uppermost leaves reduced, more shallowly lobed and distinctly clasping by their broad bases INFLORESCENCE: cymose Flowers: buds oblong, about 1.5 times as long as wide; calyx with 4-10 prickles per sepal, the sepal horn 5-12 mm long, smooth, terete, the apical prickle not basally enlarged; petals pale lemon-yellow, rarely darker yellow; stamens 20-75. Fruit: capsules ovate-elliptic to oblong with about 10-16 scattered prickles per square cm of surface, the largest ones 6-12 mm long; SEEDS numerous, pitted Misc: disturbed soil; 600-750 m (2000-2500 ft); Apr-May