Description from Flora of China
Ervum tetraspermum Linnaeus, Sp. Pl. 2: 738. 1753.
Herbs annual, 20-60 cm tall. Stem climbing, much branched, slender, puberulent. Leaves paripinnate, 2-4 cm; stipules sagittate or semitriangular, 2-3 mm; leaflets 2-6-paired, oblong or linear, 6-7 × ca. 3 mm; tendril present. Raceme ca. 3 cm, 1- or 2-flowered. Calyx obliquely campanulate. Corolla pale blue, pale violet, pale rose, or white, 4-8 mm; standard oblong-obovate; wings subequaling keel. Ovary stalked, oblong, 3-4 mm; ovules 4. Legume oblong, 8-12 × 2-4 mm, glabrous. Seeds 4, oblate-spheroid. Fl. Feb-Aug, fr. Mar-Aug. 2n = 14.
Hill slopes, valleys, grasslands, fields, cultivated areas, open ground, wastelands, roadsides; near sea level to 2900 m. Anhui, Fujian, Gansu, Guizhou, Hebei, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Sichuan, Taiwan, Xinjiang, Yunnan, Zhejiang [Afghanistan, Bhutan, N India, Japan, Kazakhstan, Korea, Kyrgyzstan, N Pakistan, Russia, Tajikistan, Uzbekistan; N Africa, C and SW Asia, N Atlantic islands, Europe; widely introduced and naturalized elsewhere].