Description

Perennial herb growing to 2 ft (60 cm). Has a square stem, oval toothed leaves, and whorls of pale lilac flowers growing from the leaf axils.

Habitat & Cultivation

Bo he is native to temperate regions of the northern hemisphere, and is widely cultivated in China. Harvested 2–3 times a year, the best crops are in early summer and early autumn.

Parts Used

Aerial parts.

Constituents

Bo he contains a volatile oil comprising mainly menthol (up to 95%) with menthone, menthyl acetate, camphene, limonene, and other terpenoids.

History & Folklore

Bo he was first mentioned in Grandfather Lei’s Discussion of Herb Preparation (c. 470 CE). A 15th-century Chinese prescription recommends bo he for dysentery with blood.

Medicinal Actions & Uses

In Chinese herbal medicine bo he is a popular treatment for colds, sore throats, sore mouth and tongue, and a host of other conditions ranging from toothache to measles. Like peppermint (M. x piperita), it helps to lower the temperature, has anti-mucus properties, and may be taken for dysentery and diarrhea. The juice has also been used to treat earache. Bo he is often combined with ju hua (Chrysanthemum x morifolium) to treat headaches and bloodshot or sore eyes.

Related Species

The Japanese variety of bo he (M. arvensis) is widely cultivated as a source of menthol. The closely related spearmint (M. spicata) native to Europe and Asia, is used mainly as a flavoring and culinary herb. See also peppermint (M. x piperita) and pennyroyal (M. pulegium).