Motherwort is an erect perennial that was introduced to North America and has now naturalized. It grows from 18 inches to five feet on stout, ridged, prominently square , hollow, greenish stems with a few ascending branches.
Leaves are dark green, thin, floppy looking, with a slight rough surface due to fine hair. The larger lower leaves are palmately divided, usually with 5 pointed lobes and from 3 to 4 inches wide. The stalks are as long as the blade causing the drooping look and they are also 4-angled with dense hair on the angles. Middle stem leaves will have 3 lobes and small upper leaves can be lance shaped without lobes. All leaves are prominently veined and have wedge-shaped bases.
The inflorescence is a series of numerous whorled clusters containing 6 to 15 flowers, arranged around the stem at the leaf axils of the upper leaves. In the mint family this arrangement is called a 'verticillaster' where the flowers look like a whorl arrangement but are actually in cymes that rise from the axils of opposite bracts.
Flowers: Individual tubular flowers are usually stalkless and composed of a broad upper lip that is hairy on the upper side and slightly recurved, and then a lower lip split into a center lobe and two side lobes. The side lobes recurve and fold under the center lobe. These corolla parts are usually whitish on the outside and pinkish to purplish on the inside and short - 1/3 to 1/2 inch long. There are 4 stamens, paired, the 2 in front being the longest, and one style. The outer calyx tube is green with 5 sharp pointed teeth. Each flower is shorter in length then the leaf stalk it is next to.
Fruit: Flowers mature to a brown capsule with 4 brown nutlets that are 3-angled, 2 to 3 mm long, and with fine bristly hair on their apex.
Habitat: Motherwort grows best in partial sun with moist rich soil. It will show up along woodland edges and disturbed areas. It grows from a rhizomatous root system which will from colonies by the spreading of the rhizomes. It is not considered invasive by any state.
Names: The genus name Leonurus, is from the Greek meaning 'lion's tail' which the plant was thought to resemble. The species name, cardiaca, refers to 'the heart' and references the old medicinal use of the plant as explained below. The common name of Motherwort is also explained below by Culpepper. The author name for the plant classification, 'L.', refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.
Comparisons: Members of the mint family tend to have flowers in what look like whorls around the stem at the leaf axils. Motherwort's lobed leaves are distinctive. Compare Wild Mint, Mentha arvensis.
Above: The inflorescence in the upper stem section. Illustration by Dr. Otto Thome.
Above: 1st photo - A flower raceme showing how flower verticillasters form in the leaf axils. 2nd photo - Lower stem leaves will show the most palmately divided leaves. 3rd photo - Mid stem leaves have a reduced number of lobes. Only the very upper new leaves may be without lobes.
Below: Individual flowers have an extremely hairy upper lip. The inside of the lower lips and the anthers are a darker purple. Note the angled stem with fine hair on the angle. Note also that the angled leaf stalk is longer than the flowers.
Below: Seed capsules - each flower produces 4 nutlets. Many can be seen on the late summer stalk (1st photo) arranged with the each capsules squared off sides tucked next to each other . By early winter (2nd photo) most of the dark 3-angled seeds have been dispersed. The stalk remains persistent into winter.
Notes: Motherwort is an introduced plant not native to the Garden. Eloise Butler liked it enough to plant it in 1912 with plants sourced at what is now Minnehaha Park in Minneapolis. She brought in more in 1919 two times. Motherwort is found throughout the U.S. except California and Florida and all of southern Canada except Labrador and Newfoundland. In Minnesota it appears in over half of the counties with most exceptions being in the north half of the state.
Uses and Lore: Motherwort is a native of Asia that made its way to Europe and then to North America with the settlers who used it as a herb for medicinal purposes, especially in the preparations of tonics and decoctions for strengthening palpitations of the heart. (see Hutchins Ref. #12). The tops and leaves of the plant were used. Culpepper in The English Physician writes: "There is no better herb to take melancholy vapours from the heart, strengthen it, and make a merry, chearful, blythe soul, than this herb. It may be kept in a syrup or conserve; therefore the Latins called it Cardiaca. Besides, it makes women joyful mothers of Children, and settles their wombs as they shoud be, therefore we call it Motherwort. It is held to be of much use for the trembling of the heart, and faintings and swoonings; from whence it took the name Cardiaca." (Ref. #4b, Pg. 215)
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"