Chinese motherwort

Chinese motherwort (Leonurus japonicus) is an annual or biennial herb of the mint family (Lamiaceae), 30–120 cm tall, with square, branching, finely hairy stems. The leaves are opposite and variable: the basal and lower leaves are large and deeply divided into 3–5 lobes with toothed margins, while the upper leaves are smaller with fewer lobes. The flowers are small, pink to pale purple, borne in whorls at the leaf axils; the two-lipped corolla is hairy, with a hooded upper lip and a three-lobed lower lip, and is bee-pollinated. The fruit consists of four small brown nutlets held in the persistent calyx. The whole plant has a mild aroma and a bitter-pungent taste.

Chinese motherwort is distributed across East Asia (China, Vietnam, the Korean Peninsula, Japan) and many tropical and subtropical regions; it grows wild along roadsides, field edges and waste ground and is cultivated as a medicinal herb. It is an important herb in traditional medicine, its name meaning "beneficial to mothers": it is used to regulate menstruation, invigorate the blood, resolve stasis and treat menstrual disorders, dysmenorrhoea, retained lochia and postpartum complaints. Its main actives are the alkaloids leonurine and stachydrine. In Vietnam the plant grows wild in many places and is cultivated for medicine; motherwort extract is widely sold.