Argemone mexicana Linnaeus var. ochroleuca (Sweet) Lindley

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.