Description from Flora of China
Annuals. Stems erect or ascending, simple or branched and diffuse, 5-30 cm tall, with white multicellular hairs often concentrated along 2 lines. Leaves often 3-5 pairs, lower ones short petiolate, upper sessile; leaf blade ovate-orbicular, 5-15 X 4-10 mm, hirsute, margin crenate, veins 3-5. Racemes terminal, lax, elongated to 20 cm, many flowered, with multicellular glandular hairs; bracts alternate, leaflike, lower ones narrowly ovate and sparsely crenate, upper ones narrowly elliptic and entire. Pedicel less than 2 mm. Calyx 4-lobed, 3-4 mm; lobes linear-lanceolate, lower 2 lobes longer than upper 2. Corolla blue to blue-purple, rotate, ca. 2 mm, shorter than calyx; lobes orbicular to narrowly oblong. Stamens shorter than corolla. Capsule obcordate, strongly compressed, 2.5-3.5 X 3-4 mm, glabrous, margin glandular ciliate, apex notch very deep; lobes rounded-obtuse. Style less than 1 mm, shorter than to equalling notch. Seeds oblong, ca. 1 mm, smooth. Fl. Apr-May. 2n = 16.
Naturalized in waste grassy places and along roads; below 2000 m. Anhui, Fujian, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shandong, Taiwan [native to S Europe and SW Asia, naturalized over most of the world].