Plants annual, 20-40 cm tall, glabrous. Stem erect, simple. Leaves alternate, shortly petiolate or upper leaves subsessile; petiole 1.5-3 cm; leaf blade pale green abaxially, dark green adaxially, ovate or ovate-lanceolate, 6-8 × 3.5-4 cm, membranous, without glands or with few ciliate glands at base, lateral veins 4 or 5 pairs, base cuneate, attenuate into petiole, margin coarsely serrate, teeth mucronulate, apex acute or acuminate. Inflorescences in upper leaf axils, 2-or 3-flowered; peduncles longer than petioles, slender. Pedicels 1-1.5 cm, bracteate at base (but appearing as if at middle in upper flowers); bracts ovate, 2-5 mm, apex cuspidate. Flowers red or purplish red, large, 2-2.5 cm. Lateral sepals 2, orbicular or elliptic, 5-6 × 3-4 mm, 5-veined, apex long mucronulate. Lower sepal subsaccate-funnelform, ca. 2.5 cm deep, narrowed into an incurved spur; spur red striate, shorter than limb; mouth oblique, ca. 1.5 cm wide, tip acute. Upper petal orbicular, ca. 1.5 cm in diam., apex curved, long mucronulate, abaxial midvein thickened, carinate; lateral united petals not clawed, 2-2.5 cm, 2-lobed; basal lobes orbicular; distal lobes curved, narrowly dolabriform or falcate, longer, apex obtuse (or ?mucronate); auricle inflexed, narrow. Filaments subulate, short; anthers ovoid, apex acute. Ovary erect, fusiform. Capsule linear, ca. 1.5 cm. Fl. Sep.