A Contribution to Our Knowledge of Leonurus L., I-mu-ts'ao, the Chinese Motherwort
Authors: Hu Shiu-ying 
Published: November 2004

This article deals with the ethnobotanical aspects of the Chinese motherwort. Since time immenmorial the Chinese people have used various parts of motherwort to meet different physical needs. By the time a written language was developed and the medical uses were recorded, motherwort was treated as an article of superior quality. At present, under the name of i-mu-ts'ao, the plant is used for improving bloodflow both by official physicians and herbal practitioners throughout the country as well as by villagers in isolated areas.

Accroding to Chinese classical literature on materia medica, the early uses were limited to the parts of the plant which met the most obvious needs of the prehisotrical people in their struggle for existence - food and pain reliever. Evidently, in their search for food, the ancient people found that the four nutlets contained in the dry and spinose calyx of the Chinese motherwort resemble the sesame seed in size and oil content. They gathered them and used them for food in similar manner as with the sesame. Consequently, they discovered the good effects to the eyesight, the improvement of strength, and the uplift of spirit. These discoveries led to the use of the seed of the species as an eye medicine for improving the eyesight, and as a tonic for the increase of strength and the elevation of medicine for improving the eyesight, and as a tonic for the increase of strength and the elevation of spirit. Contagious skin diseases caused serious problems for the ancient people. The use of the leafy shoot for a bath to release the discomfort of itches and shingles was also recorded in the 42-word first medicinal second of the species in the earliest known Chinese materia medica - the Shen-nung pen-ts'ao-ching.

Translators of the Chinese classics have included the records of i-mu-ts'ao. According to my knowledge, these works were all partial translations with the selections of the medicinal properties and the omissions on the methods of preparation. They have the outline and abandon the details. Consquently most of the them are not clear. In order to provide complete information on the discoveries of the ancient Chinese people on the uses of i-mu-ts'ao, all the records up to the end of the sixteenth century are organized and translated under the following headings: (1) ecological and morphological observations; (2) preparations; (3) physical and therapeutical properties; (4) special prescriptions for interanl and external uses - including pills for pregnant women, for mothers post partum, as an emmenagogue, and as a corrective agent, condensed liquid, powder, fresh juice, baby bath and washes, poultices, charred shoots, gargles, drops and cakes; (5) other economic uses - including cosmetics and food; and (6) etymology.

The distribution of i-mu-ts'ao is significant in photogeography and in the nomenclature of the species. I-mu-ts'ao was purposely introduced from South China to Linnaeus in Sweden before the publication of the Species Plantarum in 1753. Linnaeus planted the seed in the botanical garden of the University of Uppsala. Due to the differences in temperature, length of the growing season and the periodicity of the sun between Sweden and South China, the plant flowered but did not fruit in Uppsala. Linnaeus observed this fact and assumed it being a male plant of Leonurus sibiricus L. In his book, after China, he put a sign () indicating male.

I-mu-ts'ao was unintentionally introduced by Portuguese with the wrappings of Chinese products - silk, sugar, medicine, tea, porcelain, etc. - to the sugar plantations in Brazil. There are the temperature, growing season, periodicity of the sun and the rainfall are comparable to the maritime provinces of China and the species got established and became a weed. A British traveler saw the species in Brazil in the late 1820s and seeds to London. When the plant flowered, Robert Sweet named and described it as Leonurus heterophyllus Sweet. Now in China this name is accepted as the specific epithet of i-mu-ts'ao. Leonurus heterophyllus Sweet (1827) is a latter homonym of Stachys artemisia Lour. (1790) and it cannot be a legitimate name for i-mu-ts'ao.

The genuine species of Leonurus sibiricus L. is typified by a specimen in Linnaeus's herbarium (marked 739.6), collected from Siberia by Gmelin. Linnaeus's Chinese specimen (now numbered 739.7) is conspecific with the population studied, sampled and described by Loureiro in Canton-Macao area under the name Satachys artemisia Lour. Now the proper scientific name for i-mu-ts'ao of the maritime provinces of China is Leomurus artemisia (Lour.) S.Y. Hu.

Is the development of i-mu-ts'ao, there are marked morphological changes from the juvenile form to the flowering stage and to the fruiting plant. In addition to the systematic translation of the ancient Chinese records on the uses of i-mu-ts'ao, the mapping and the interpretation of the geographical distribution of the species, the comments of certain names in Chinese and the correction of the scientific name, an illustrated account of the field observation made in Chung Chi College, The Chinese University of Hong Kong, is given.