About Leonurus japonicus Houtt.
Leonurus japonicus Houtt. is an annual or biennial plant that grows from a taproot. Its upright stems reach a height of 30 to 120 cm (12 to 47 in). The sessile flowers grow in verticillasters. The calyx is tubular-campanulate, 6 to 8 mm (0.24 to 0.31 in) long, and has broad triangular teeth. The corolla ranges in color from white, to reddish, to purplish red. This plant blooms from June to September. It has escaped cultivation and naturalized in other regions around the world, including North and South America, Europe, and Africa.
In traditional Chinese medicine, Leonurus japonicus is counted among the 50 fundamental herbs. It is known in Chinese as yìmǔcǎo (益母草), which translates literally to "beneficial herb for mothers". It is used to treat menstrual and delivery disorders caused by blood stasis, such as dysmenorrhea and amenorrhea.
