Plants annual, to 90 cm tall. Stem erect or ascending in lower part, robust, succulent, branched, glabrous, nodes swollen in lower part, with many fibrous roots. Leaves alternate; petiole 4-8 cm; leaf blade elliptic, 5-10 × 3-4 cm, glabrous, lateral veins 5-7 pairs, curved, base cuneate, margin coarsely crenate, teeth mucronulate, apex caudate-acuminate. Inflorescences 1-flowered; peduncles ca. 1 cm, to 2 cm at fruiting. Pedicels 2-bracteate above middle; bracts persistent, ovate-lanceolate, ca. 3 mm, herbaceous. Flowers yellowish. Lateral sepals 2, broadly ovate, ca. 1 × 0.5-0.6 cm, membranous, 9-veined, margin entire, apex mucronulate. Lower sepal yellow striate, saccate, abruptly narrowed into a hooked spur; spur ca. 8 mm, 2-lobed. Upper petal suborbicular, ca. 1 cm in diam., apex emarginate, shortly rostellate, abaxial midvein green cristate; lateral united petals clawed, 1.5-2 cm, 2-lobed; basal lobes oblong, small, apex acuminate or caudate; distal lobes dolabriform, large, apex obtuse; auricle obtuse, cornute. Filaments linear, slightly swollen above; anthers ovoid-orbicular, apex obtuse. Ovary erect, fusiform. Capsule linear-cylindric, 3-3.5 cm. Seeds many, brown, subglobose, smooth. Fl. Jul-Sep. 2n = 20*.

● Forest understories, moist places in valleys, grasslands; 300-700 m. Anhui, Fujian, Guangdong, Hubei, Hunan, Jiangxi, Zhejiang.