Description from Flora of China
Annuals, 40-90 cm tall. Stems erect, 1 or few, often apically much branched, rarely in whorls of 3, angled, striate, puberulent. Leaves opposite or sometimes upper leaves alternate; lower leaves dissected, segments narrow; upper leaves undivided; leaf blade linear, 3-6 cm, margin entire. Racemes in panicles; bracts to 1 cm. Pedicel ca. 1 cm, slender, flexuous. Bracteoles 2, needlelike, near apex of pedicel. Calyx 10-ribbed; lobes triangular, wider than long, apex acute to obtuse, inside and margin lanose; sinuses angled. Corolla yellow to purple; tube ca. 3 mm; lobes orbicular-obovate, ca. 5 mm, subequal, apex rounded. Filaments flattened; fertile anther locules oblong-ovate, ca. 2.5 mm, densely comose at base; sterile anther locules clavate, ca. 1 mm, stipitate. Capsule globose, glabrous, almost as long as or shorter than persistent calyx. Style persistent. Fl. Jun-Jul, fr. Sep.
Grassland on mountain slopes, fields; 1600-2100 m. Guangdong, Guangxi, Guizhou, Hunan, Jiangxi, Sichuan, Yunnan [Bhutan, India, Indonesia (Java), Laos, Malaysia, Nepal, Pakistan, Philippines, Sikkim; Africa].