Perennial twining herbs, stems longtitudinally striate, occasionally verrucose, glabrous to hirsutulous with stiff yellowish trichomes.
Petioles slender, glabrous or rarely with scattered yellowish trichomes, 6-20 mm long. Leaves palmate, leaflets (3,4)-5, with the median the largest, leaflets entire, ovate-lanceolate, bases acute to attenuate, margins entire, midribs prominent especially on the lower leaf surfaces, apices attenuate, mucronate, 15-40 mm long and 7-14 mm wide.
Flowers solitary, axillary, penducles 1.5-2 times as long as the subtending petioles; bracts reduced to scales or missing; pedicels nearly equal in length to the peduncles, clavate.
Sepals subequal, the outermost shorter, elliptic-ovate to orbicular, margins membranous, apices mucronulate, in fruit the. calyx becomes chartaceous, the mucros more noticeable, and the lower inside surfaces of the sepals pocked with glands, the backs of the outer sepals and the upper exposed portions of the inner sepals may be sparsely appressed stellate pubescent, the margins glabrous and scarious, the outer sepals 20-30 mm long and 12-15 mm wide, the inner 23-33 mm long; corolla campanulate, bright yellow with a dark purple throat; the limb shows five distinct bands, each five-nerved; corolla entirely glabrous, 55-60 mm long and 55-65 mm wide; stamens five, unequal, not protruding from the throat, filaments basally adnate to the corolla tube, bearded where attached, glabrous above, dark purple-black, 10-15 mm long, anthers spirally dehiscent at maturity, yellow, 7-12 mm long, pollen three colpate, smooth; ovary conical, 2-3 mm tall, glabrous, two celled, each with two ovules, disc annular, glabrous, smooth, style filiform, simple, glabrous; dark purple, 13 mm long, stigma biglobose, lobed and papillose.
Pollen three colpate, smooth.
Fruit a chartaceous four-valved capsule, frequently with style base persisting, tan to brown, surrounded by the accrescent calyx.
Seeds four, black, puberulent, carinate, 8-11 mm long, with a distinct hilum.