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.
FNA Vol. 3
Duration: Annual Nativity: Native Lifeform: Forb/Herb General: Herbaceous annuals to perennials, to 1 m tall, stems stout,and branching distally, with sparingly prickly surfaces. Leaves: Alternate, basal leaves in a basal rosette, shallowly to often deeply lobed, proximal blades deeply lobed nearly to the midrib, distal blades more shallowly lobed and usually clasping, margins dentate, each tooth terminated by a prickle, surfaces glaucous, often mottled over veins, lower surfaces sparingly prickly on veins, upper surfaces usually unarmed. Flowers: Lemon or darker yellow, large and showy, 3-7 cm broad, with large, delicate petals with rounded tips, buds oblong, 8-18 mm long and 4-11 mm wide, with 4-10 prickles per sepal, sepals 2-3, unarmed or prickly, each with an erect, subterminal, unarmed, hollow horn, sepal horns terete, 5-12 mm, unarmed, stamens 20-75, filaments yellow, pistil 3-6-carpellate, ovaries 1-locular, styles short, to 3 mm long in fruit, stigmas 3-7-lobed, infloresences terminal, cymose, with subtending bracts. Fruits: Ovoid-ellipsoid to oblong capsules 20-50 mm long and 10-18 mm wide (including stigma and excluding prickles), longest prickles 8-12 mm long, fruits erect and dehiscing from the apex, with persistent valves, styles, and stigmas, surfaces scattered-prickly Ecology: Introduced, found on disturbed soil, often a weed of fields, roadways, embankments, and intermountain plains, around 7,500 ft (2286 m); flowering and fruiting spring-fall. Distribution: Arizona, Mexico. Notes: This species has large, bright to deeply yellow flowers and moderately prickly surfaces. Ethnobotany: Specific uses for this species are unknown, but other species in the genus have uses. Synonyms: Many, see Tropicos. There is some uncertainty about this taxa and whether it includes A. mexicana. Editor: LCrumbacher2012 Etymology: Argemone comes from the Greek argemos, "a white spot (cataract) on the eye," which this plant was once supposed to cure, and ochroleuca means yellowish-white, the color of the flowers.