Description from Flora of China
Herbs annual, erect, 10-40 cm tall. Primary roots orange, stout. Stems and branches terete, white flattened-villous. Leaves subopposite, subsessile; leaf blade green, broadly elliptic or oblong-elliptic, 1.5-3 × 1-2 cm, papery, both surfaces villous, midvein slightly raised abaxially, slightly impressed adaxially, lateral veins 3 or 4 pairs, slightly raised and indistinct abaxially, veinlets absent, base rounded to cordate, margin entire, ciliate, apex obtuse, mucronate. Racemes supra-axillary; peduncles 5-10 mm, villous; bracts 3, caducous, sometimes persistent, subulate, ciliate. Sepals 5, persistent, ciliate; outer sepals 3, ovate, unequal, 2-3 mm, outside villous, apex acuminate; inner sepals 2, falcate, obliquely ovate, ca. 5 × 2 mm, green, 5-veined, base unguiculate, apex acuminate-acute. Petals 3, connate at base, white or yellow; lateral petals oblong, ca. 4 × 2 mm, inside fasciculate white villous at middle; keel cucullate, ca. 5 mm, apex with stalked, fimbriate appendages. Stamens 8; filaments ca. 4 mm, lower 1/2 forming a staminal sheath split at top, adnate with petals; anthers ellipsoidal, stalked. Ovary obovoid, ca. 1.3 mm in diam., narrowly winged, ciliate; style slightly arcuate, apex hooklike; stigma in hook. Capsule green when mature, suborbicular, wider than long, ca. 4 mm in diam., winged, ciliate, apex incised, white villous. Seeds 2, black, ellipsoidal-ovoid, compressed, ca. 3 mm, ca. 1.5 mm in diam., white villous; strophiole 2-lobed, other end with brown small tubercle. Fl. and fr. Aug-Nov.
● Shrub forests, grasslands on slopes or in valleys; 600-1400 m. SW Guizhou (Anlong, Zhenfeng), Sichuan, S Yunnan (Xishuangbanna).