Northern Bugleweed is a native semi- erect perennial forb growing on square hollow stems up to 40 inches high. They may be sparingly branched or un-branched, with sparse hair or none at all. A vertical groove is on each side of the stem. Stems are weak and will sprawl without adjacent plant support.
Leaves are opposite, each pair rotated 90 degrees from the adjacent pairs, elliptic to lance-like, tapering to a pointed tip. The leaf is not lobed but has coarse shallow well spaced marginal teeth. The base of the leaf tapers to a wedge shape and then along the stalk, sort of like a wing. Leaves reduce in size toward the top of the stem and may be stalkless at the top. The upper surface is medium to dark green (sometimes purplish in full bright sun). The under side is a paler color and pitted, and can have sparse hair on the main veins. Leaves do not have a mint aroma.
The inflorescence has a number of tight whorl-like clusters of small flowers around the leaf axils in the upper section of the stem. The clusters are not whorls but are called 'verticillasters', where the flowers look like a whorl arrangement but are actually in cymes that rise from the axils of opposite bracts. Only a few flowers in each cyme open at one time.
The flowers are small, 5-parted, with either a very short stalk or none at all (sessile). The green calyx is very short, with the 5 sepals united in a tube shape, from 1.7 to 3.5 mm long with the upper part of the tube separated into 5 pointed triangular teeth (the only Lycopus species in our area with 5 teeth), obtuse at their tips, the tips less than 1/32 inch (0.8 mm) long. The corolla has 4 to 5 white petals that are united at their bases to form a tube. The entire corolla is less than twice to twice the length of the calyx. The tube then separates into a 2-lobed upper lip and a 3-lobed lower lip. The upper lip may be notched only and not look like two distinct lobes giving the overall appearance of only four lobes. Flowers have 4 stamens, two of which are sterile (staminodes) and remain within the corolla, while the two fertile stamens have yellow anthers (brownish at pollen maturity) and, with the style, are exserted from the corolla. Flowers are not fragrant.
Fruit: Like many mints, the seed cluster has 4 nutlets. These are brown, 3-angled, ovoid, with one seed each. Nutlets when mature, are slightly longer than the calyx tube, flattened and indented on the side toward the center of the cluster with tubercles at the upper end. (Tubercles are lighter airy cell structures that allow seeds to float on water for dispersal). The nutlet cluster appears depressed across its top. If one wanted to propagate plant it would best to use a root division.
Habitat: Northern Bugleweed grows from a horizontal tuberous roots with other fibrous roots. An above ground stolon grows and develops a tuber at its tip to form a new plant the following year. It is a plant of moist meadows, marshes, streambanks and other low grounds that are wet to wet-mesic with full to partial sun.
Names: The genus Lycopus is derived from two Greek words, lykŏs, meaning 'wolf' and pŏus, meaning 'foot', which Stearn (Ref. #37a) maintains is from "some fancied resemblance to a wolf's foot." The species name, uniflorus, is derived from uni and florus and meaning 'one-flowered' and the name came about from the plants collected by Michaux near lake St. John in Quebec and his description published 1803 (Fl. Bor.-Amer.) after his death. These plants were young and just beginning to flower, at which time there may have been only one or so flowers open on the collected plants, hence 'one-flowered'. These specimens are in the herbarium of Jussieu (Jardin des Plantes). [This description from M. L. Fernald, June 1904, Rhodora, Vol. 6, No. 66.] The variety name, var. uniflorus, is currently used to designate this species as the one from previous classifications where it was sometimes listed as Lycopus virginicus L. var. pauciflorus. There are no other varieties accepted. 'Bugleweed' comes from the shape of the flower. As to the alternate common name of 'Horehound', see the "medicinal notes" at the bottom of the page.
The author name for the plant classification - ‘Michx.’ refers to Andre Michaux (1746-1802), French botanist who made many exploring expeditions in the U.S. collecting and cataloging many species. His notes were later used by his son, Francois, who with Thomas Nuttall published the multi-volume North American Sylva.
Comparisons: There are three other Bugleweeds found in Minnesota which have the same general habitat. L. asper, Rough Bugleweed; L. americanus, American Water Horehound; and L. virginicus, Virginia Water Horehound. Differences are found in the amount of hair, in the leaves, length of the calyx teeth and number of calyx lobes; and the root system. Virginicus lacks tubers. Asper and americanus have longer calyx tips - 1/16 to 1/8 inch and these surpass the mature nutlets. All 3 have only 4 calyx lobes whereas uniflorus has 5. Only virginicus has dense hair on the stem and hair on both leaf surfaces. All 3 have more coarse deeper teeth with americanus having the lower leaves with lobes also. Asper does not have leaf stalks. Only virginicus has a nutlet cluster where the top is flat not depressed. Virginicus is the one you may less-likely encounter as it is on the state "watch" list.
Above: Northern Bugleweed usually has an unbranched stem with the flower clusters in the leaf axils of the upper section. Drawing from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.
Below: 1st photo - The inflorescence is a verticillaster - two cymes, placed on opposite sides of the stem at the leaf axil. 2nd photo - individual flowers have a corolla longer than the calyx, 5 lobes - two united to form an upper lip and 3 forming the lower lip lobes. The two fertile stamens are visible.
Below: 1st photo - Leaves are elliptic to lance-shaped with coarse shallow teeth. 2nd photo - the leaf underside is paler, some sparse fine hair on the mid-vein of this example, and dotted.
Below: 1st photo - the stem is 4-angled and grooved, this example with sparse fine hair. 2nd photo - the nutlets are 3-angled, ovoid, with a flattened depressed side and rounded on the other sides. At the tip are some knobby tubercles. Photo - ©Steve Hurst, USDA-NRCS Plants Database.
Notes: Northern Bugleweed is indigenous to the Garden. Eloise Butler first noted it in her log on August 16, 1915 when she spotted it in bloom. It has been on all the census reports since. In Minnesota the plant is widespread, found in most counties with the exceptions being mostly in the southwest and western part of the state where it is drier. In North America it is commonly found, only known to be absent in the southern tier of U.S. states from Florida west to Arizona and in the far northern Canadian Provinces.
Medicinal uses: The various species of Lycopus have been used in folk medicine for cough remedies. (Ref. #39) It was this use that gave the plants the alternate name of 'horehound' as this references back to the Romans and the Egyptians that used the plant they called 'horehound' for such purposes. Their plant was Marrubium vulgare and since the Lycopus prefers moist environments, we have 'water horehound'. An extract of Lycopus uniflorus has been studied at the School of Pharmacy, Lebanese American University, for anti-inflammatory, anti-ulcerogenic and antioxidant activities and test results show that the species has such activites. (Saade, Ziadeh, Ramia, Daher, Mroueh - 2009)
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"