Plants perennial, 20-70 cm tall, glabrous, with a procumbent tortuous subterranean stem. Stem succulent, simple, swollen at middle and lower nodes. Leaves alternate, crowded at apex of stem, sessile or shortly petiolate; leaf blade oblong-lanceolate or broadly ovate-elliptic, 5-18 × 2-5 cm, setulose between teeth, lateral veins 7-9 pairs, conspicuous on both surfaces, base cuneate, decurrent into petiole, margin crenate, apex acuminate or acute. Inflorescences in upper leaf axils, racemes 3-8(-13)-flowered; peduncles overtopping or ca. as long as leaves, strict. Pedicels 2-3 cm, bracteate at base; bracts caducous, ovate or navicular, 5-8 mm, leathery, apex acuminate. Flowers yellow or yellow-white, 1.6-2.2 cm deep. Lateral sepals 4; outer 2: broadly ovate, 8-10 × 4-5 mm, inequilaterally veined, apex acuminate; inner 2: linear-lanceolate, 1-1.4 cm, hyaline, 1-veined, apex curved. Lower sepal incurved, red-brownish striate, saccate, 2.5-3.5 cm deep, gradually narrowed into an incurved or involute spur 1.4-1.7 cm; mouth vertical, 1.5-1.8 cm wide, tip acute. Upper petal broadly elliptic or obovate, 1.4-1.6 cm, membranous, apex cuspidate, abaxial midvein slightly thickened; lateral united petals broadly clawed, ca. 2 cm, 2-lobed; basal lobes obovate; distal lobes longer, oblong or subdolabriform, apex rounded or emarginate; auricle inflexed, triangular. Filaments linear; anthers obtuse. Ovary fusiform, long rostellate. Capsule unknown. Fl. Oct.