A Prickly glabrous annual herb, 30-125 cm tall, branched. Leaves alternate, elliptic-oblong, pinnatifid, semiamplexicaul, sinuate-lobulated; variegated green and white, 5-20 cm long, 2-8 cm broad, ultimate segments, dentate, prickly on the margin, midrib and the veins beneath; Flowers sessile, 3-8 cm in diam., subtended by 2-3 foliaceous bracts. Sepals 8-12 mm long, 5-7 mm broad, with an acute, terete horn below the apex, very sparsely prickly outside, concave, imbricate caducous. Petals 4-6, obovate, 2.5-3.5 cm long, (1.5-)2-2.5 cm broad, narrowed below, bright yellow, imbricate, more or less crumpled in bud. Stamens indefinite, 8-12 mm long; anther c. 2 mm long, curved after flowering. Ovary ovate, 8-10 mm long, 3-5 mm broad covered with long soft spines; stigma red, 3-6 lobed; lobes usually broad. Capsule, oblong or elliptic-oblong, 2.5-4 cm long, 1.2-2 cm broad, with rounded ribs, covered with sharp erect prickles; valves 3-6. Seeds many, blackish brown to brown, ± rounded, 1.5-2 mm in diam, with fine, con¬spicuous tuberculae.
Plants annual. Stems often branching from base, 2.5-8 dm, unarmed or sparingly prickly. Leaf blades: surfaces unarmed or sparingly prickly on veins; proximal lobed 1/2 or more distance to midrib; distal more shallowly lobed, mostly clasping. Inflorescences: buds subglobose, body 10-15 × 9-13 mm, unarmed or sparingly prickly; sepal horns terete, 5-10 mm, unarmed. Flowers 4-7 cm broad, subtended by 1-2 foliaceous bracts; petals bright yellow or rarely pale lemon yellow; stamens 30-50; filaments yellow; pistil 4-6-carpellate. Capsules oblong to broadly ellipsoid, 25-45 × 12-20 mm (including stigma and excluding prickles when present), unarmed or prickly, longest prickles 6-10 mm. Seeds 1.6-2 mm. 2 n = 28.