Leonurus japonicus aka Chinese Motherwort

Leonurus japonicus is an upright herb in the mint family, Lamiaceae. It comes from east Asia, including China. It now grows through much of Asia's tropics and subtropics. Useful Tropical Plants says it has spread beyond its native range. It grows on hills, by roads, on waste ground, and in gardens. In China, it grows up to about 11,155 feet [3,400 metres] above sea level. It is not native to Britain or Ireland.

Sources differ on how long it lives and its height. Plants For A Future says it lives one or two years. It gives a height of 3 feet [0.9 metres]. Useful Tropical Plants says it may live for several years, though not long. It describes a tuberous rootstock, a swollen base from which roots grow. Its full account gives heights of 1.6–4.9 feet [0.5–1.5 metres]. Both sources use 3 feet [0.9 metres] as a guide height. Neither gives a clear spread for plants grown in gardens. They say little about leaf shape or how stems feel.

Plants For A Future says it blooms from July to September. Seeds ripen in August and September. Each flower has both male and female organs. Bees move pollen between the flowers. The text gives no flower colour or fruit shape. Its value to bees gives it a role in planted beds. The evidence shows no other traits for show or garden uses.

The plant grows in sun or part shade and prefers moist soil. Plants For A Future lists sand, loam, and clay as suitable soils. It lists soils that are slightly acid, neutral, or slightly alkaline. Useful Tropical Plants says it grows in poor soil. Plants For A Future warns about its growing notes. Some reflect the needs of the genus as a whole. That source does not say if it lives through British winters. It suggests sowing seed in a cold frame in spring. Move seedlings to their own pots, then outside in summer.

The plant has a long history in Chinese herbal medicine. People gather wild plants and sell them in local markets. Reported uses include leaves, dried flowers, stem juice, and fruit. These past uses do not prove that treatments work or are safe. Both plant-use sources list no known food uses or hazards. This does not prove safety for people or pets. Neither source names pests or diseases that cause problems. They differ on its weed risk. Plants For A Future says it is not a weed. Useful Tropical Plants flags a weed risk. It says the plant now grows wild in many places beyond its native range.