Stout annual herb, up to 2.5 m tall; young stems with short stiff simple hairs. Leaf-blades suborbicular in outline, up to c. 25 x 25 cm, 5–7-lobed or parted, with short stiff simple hairs on both surfaces; petiole up to 30 cm long. Flowers in leaf axils. Epicalyx bracts 7–12, linear to lanceolate, up to 25 mm long, present at time of flowering but later falling off. Calyx acuminate in bud, 3–4 cm long, rough outside. Petals yellow or white with dark purple base, 4–8 cm long. Capsule narrowly ellipsoid, usually 8 cm or more long. Seeds c. 5 mm long, depressed-globose, with concentric lines, sometimes pilose.