Plants annual, small, 15-25 cm tall. Stem erect or ascending from base, succulent, simple, naked in lower part, with many fibrous roots, sparsely yellow-brown pubescent in upper part. Leaves alternate, often crowded at upper part of stem; petiole 1-2.5 cm, laxly or densely yellow-brown pubescent; leaf blade pale green abaxially, dark green adaxially, narrowly lanceolate or oblanceolate, 3.5-10 × 1-2 cm, with 2 or 3 pairs of setose glands at basal margin, abaxially yellow-brown pubescent or only veins pilose, adaxially adpressed strigose, lateral veins 7-9 pairs, base narrowly cuneate, margin crenate-serrate, teeth curved-mucronulate, apex acuminate or shortly caudate. Inflorescences in upper leaf axils; peduncles conspicuously shorter than leaves, 2.5-3.5 cm, sparsely pilose. Pedicels bracteate at base (but appearing as if at middle); bracts linear or linear-lanceolate, ciliate. Flower solitary, yellow, large, 4-4.5 cm deep. Lateral sepals 2, ovate or oblong-ovate, 1-1.2 cm × ca. 6 mm, with multicellular hairs abaxially and at margin, 5-veined, apex acute. Lower sepal broadly funnelform, ca. 2 cm deep, sparsely pilose, gradually narrowed into an incurved spur ca. 2.5 cm; mouth oblique, ca. 2 cm wide, tip acute. Upper petal cucullate, orbicular, ca. 1.2 cm in diam., sparsely multicellular pubescent, apex emarginate, mucronulate, abaxial midvein conspicuously carinate; lateral united petals shortly clawed or ± clawed, ca. 2.2 × 1-1.2 cm, 2-lobed; basal lobes suborbicular; distal lobes broadly dolabriform; auricle inflexed, lunar. Filaments linear, 5-6 mm, apex dilated; anthers ovoid, apex obtuse. Ovary fusiform, 4-5 mm. Capsule (immature) linear-cylindric. Fl. Jul-Sep.