Stem climbing, minutely pubescent. Leaves distant, spreading; petiole 1 1/4–2 1/4 in. long; blade 4–7 in. long, 3–5 in. broad; cordate-ovate or cordate-elliptic, cuspidate, glabrous or minutely subscabrous-pubescent on both sides, or softly pubescent beneath. Stipules forming a reflexed toothed frill, connecting the petioles. Flowers in axillary pedunculate paniculate cymes 2 1/2–6 in. long, minutely puberulous on the branches and pedicels; bracts 2–3 lin. long, oblong-lanceolate, acute or acuminate; pedicels 6–9 lin. long. Sepals 2–2 1/2 lin. long, 1–1 1/2 lin. broad, ovate, acute, glabrous or puberulous. Corolla subrotate, 5-lobed nearly to the base; lobes 5–6 lin. long, 3 lin. broad, ovate-oblong, subobtuse, glabrous, very minutely ciliate along one margin, purple, with the margins and a short central stripe at the base green. Coronal-lobes very broadly obcordate, fleshy, white, 1 lin. long, 1 3/4–2 lin. broad, having a widely spreading, subulate, linear or linear-lanceolate, purple dorsal process 2–2 1/2 lin. long, acute or bifid at the apex. Follicles 3–4 in. long, 1 1/2–1 3/4 in. thick, ovoid-lanceolate, obtuse, widely divergent.