PLANT: Erect or spreading annual to 2.5 m across and 1 m high. LEAVES: simple; petioles to 25 cm long or more; blades broadly triangular-ovate to subobicular-ovate, cordate or inequilateral, rounded to obtuse at apex, to 25 cm long and nearly as broad, the margins entire to shallowly 3- to 7-lobed, the sinuses obtuse, denticulate. INFLORESCENCES: slender racemes to 2.5 dm long at maturity. FLOWERS: 5-15 per inflorescence; pedicels 1.5-3 cm long in anthesis, lengthening in fruit to about 45 mm; pedicel bract obovate to oblanceolate, 3-5 mm long; calyx bracts ovate to elliptic 3-5 mm wide; calyx 1-1.5 cm long, the lobes unequally cut one fourth to one half its length; corolla tubular-campanulate, only slightly ventricose, 2.5-4 cm long, viscidglandular without and slightly so within; corolla tube reddish-purple, pink, or white, with a bright yellow band extending along the lower portion of tube and out onto lower lobe; corolla lobes the same color as the tube but the upper lobes frequently with a single large purple or reddish-purple blotch, the upper and lateral lobes wideflaring or reflexed; filaments glandular at or below point of attachment, glabrous above; anthers 2.8-5.0 mm long; pistil as long as or longer than the stamens. FRUIT: body ellipsoid, 5-10 cm long, 1.5-3 cm thick and strongly keeled ventrally, the horns about 1 to 3.5 times as long as the body. NOTES: 3 subsp., 1 in AZ; CA, NV, NM, TX; n Mex. REFERENCES: Raul Gutierrez Jr., 2007, Vascular Plants of Arizona: Martyniaceae. CANOTIA 3 (2): 26-31.