Herbs annual, (9-)15-55(-80) cm tall, glabrous throughout, often glaucous, fetid when crushed. Stems erect, simple or branched above. Petiole of basal leaves 0.5-3 cm; leaf blade oblanceolate, spatulate, or obovate, 1-5 × 0.4-2.3 cm, base attenuate or cuneate, margin entire, repand, or coarsely toothed, apex rounded. Middle cauline leaves sessile, oblong, (0.5-)1.5-4(-8) × (0.2-)0.5-1.5(-2.5) cm, base sagittate or auriculate, margin dentate, repand, or entire, apex rounded, obtuse, or subacute. Fruiting pedicels (0.5-)0.9-1.3(-1.5) cm, slender, divaricate, straight or slightly curved upward. Sepals ovate or oblong, (1.5-)2-3(-3.3) × 1-1.5 mm, not saccate, margin white. Petals white, spatulate, (2.4-)3-4.5(-5) × (0.8-)1.1-1.6 mm, narrowed to a clawlike base ca. 1 mm, apex obtuse or emarginate. Filaments (1-)1.5-2 mm; anthers ovate, 0.3-0.5 mm. Ovules 6-16 per ovary. Fruit obovate or suborbicular, (0.6-)0.9-2 × (0.5-)0.7-2 cm, base obtuse or rounded, apex deeply emarginate and apical notch ca. 5 mm deep; wings 1-1.5 mm wide at base, 3.5-5 mm wide apically; style absent or 0.1-0.3 mm. Seeds blackish brown, ovoid, (1.2-)1.6-2(-2.3) × 1.1-1.3 mm, concentrically striate. Fl. and fr. Mar-Oct. 2n = 14*.
Roadsides, grassy slopes, fields, waste places; 100-5000 m. Throughout China except Guangdong, Hainan, and Taiwan [Afghanistan, Bhutan, India, Japan, Kashmir, Kazakhstan, Korea, Kyrgyzstan, Mongolia, Nepal, Pakistan, Russia, Sikkim, Tajikistan, Turkmenistan, Uzbekistan; Africa, SW Asia; introduced in Australia, North and South America].
This species is a cosmopolitan weed used as a medicinal plant and a source of oil. Cattle feeding on the plant develop tainted milk.
