Plants succulent, 30-40 cm tall, glabrous. Stem erect, flat, thick, simple or rarely shortly branched from middle, naked in lower part. Leaves alternate, often crowded toward apex of stem, polymorphic; petiole 1-4 cm, with 2 sessile glands at base; leaf blade greenish abaxially, ovate or oblanceolate, 4-15 × 2.5-3.5 cm, glabrous, lateral veins 8-15 pairs, base cuneate, attenuate into petiole, margin serrulate, apex acute or acuminate. Inflorescences in leaf axils, 1- or 2-flowered; peduncles very short, 2-3 mm. Pedicels 1-2.5 cm, slender, glabrous, bracteate at base; bracts persistent, ovate, ca. 2 mm, membranous. Flowers pink-purple, 2-3 cm deep. Lateral sepals 4; outer 2: orbicular or elliptic-orbicular, 8-15 mm in diam., apex cuspidate; inner 2: minute, ovate, ca. 2 mm. Lower sepal shallowly saccate or cup-shaped, ca. 1.5 cm deep, abruptly constricted into an incurved, short spur; mouth oblique, ca. 1.5 cm wide, tip acuminate. Upper petal broadly obovate or cuneate, 1-1.5 cm, apex retuse or truncate, mucronulate, abaxial midvein thickened, cristate; lateral united petals not clawed, 8-15 mm, 2-lobed; basal lobes spreading, pyriform; distal lobes dolabriform, often connate into 2-lobed lamella; auricle inflexed, triangular. Filaments linear, 4-5 mm; anthers ovoid, apex obtuse. Ovary erect, fusiform. Capsule fusiform. Seeds brown, orbicular, compressed, ca. 4 mm in diam. Fl. Jun-Jul.