Lycopus europaeus L.

Common Name: European bugleweed

Synonyms and Other Names:

Lycopus europaeus ssp. mollis (Kern.) Rothm. ex. Skalický, Lycopus europaeus var. mollis (Kern.) Briq., European bugleweed, marsh horehound, gipsywort, gypsywort

Kristian Peters ( Info

Identification: Hairy perennial herb with two-lipped flowers. Flowers small, white, tubular, with free petal lobes of no particular unique structure. Calyx with a series of spiny projections giving the flower clusters a bristly appearance. Flowers clustered in the leaf axils. Stem naked or finely downy. Leaves elongate, narrow, deeply cut with toothlike lobes. Rhizomes transverse, producing long stolons enlarged at apex,

Size: to 1.2 m in height.

Native Range: Eurasia and Asia

Great Lakes Nonindigenous Occurrences: 1st Great Lakes sighting 1903 Lake Ontario. Invaded into Lake Erie & the St. Lawrence River in 1903. Now spread throughout most of eastern North America. AL, DE, IL, IN, LA, MA, MD, MI, MS, NC, NJ, NY, OH, PA, VA, WI, WV

Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Lycopus europaeus are found here.

Full list of USGS occurrences

State/ProvinceFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
MI196820087Great Lakes Region; Huron; Lake Huron; Ottawa-Stony; Pigeon-Wiscoggin; Raisin; Western Lake Erie
NY197020083Great Lakes Region; Headwaters St. Lawrence River; Lower Genesee
OH197020083Lake Erie; Southern Lake Erie; Western Lake Erie

Table last updated 8/11/2022

† Populations may not be currently present.

* HUCs are not listed for areas where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).

Ecology: Lycopus europaeus is a perennial forb that prefers to grow in wet soils and can tolerate flooding. It can be found in fens, fen cars, dune-slacks, ditches, and shorelines (Online Atlas 2012). It can grow in a variety of soils: sandy, loamy, or clay, and acidic, neutral, or basic. European water horehound can grow in full sun to semi-shade (light woodland).

Lycopus europaeus flowers from June to September. The flowers have both male and female organs and are pollinated by bees and flies (OWC NERR 2011, Percival 1947). The seeds ripen and disperse from August to October (OWC NERR 2011).

Lycopus europaeus seeds are very buoyant and be transported via waterways (Vogt et al. 2006). Ninety percent of seeds were still float after 176 days in stagnant water or 256 days in moving water (van den Broek et al. 2005). Seeds can also withstand passing through the digestive track of several species. Cosyns et al. (2005) found that a portion of seeds were viable after being eaten by horses and cattle. Lycopus europaeus seeds that passed through the digestive track of mallard ducks had a high germination rate (>25%). It is probable that mallard ducks are responsible, at least in part, for the long-range dispersal of European water horehound (Soons et al. 2008).

In order for germination to occur, the temperature needs to be above 12°C and below 33°C (Brändel 2006). Brändel (2005) also found that seeds exposed to fluctuating temperatures had higher germination rates.

The root system of L. europaeus contains rhizomes (Online Atlas 2012).

Means of Introduction: Solid ballast

Status: Established

Great Lakes Impacts:  

Current research on the environmental impact of Lycopus europaeus in the Great Lakes is inadequate to support proper assessment.

Lycopus europaeus invades numerous wetland ecosystems and is capable of displacing natives, including L. americanus Muhl. ex W. Bartram, L. amplectens Raf., L. rubellus Moench, L. uniflorus Michx., and L. virginicus L. (USDA NRCS 2012).

Hybridization between L. europaeus and L. americanus can occur when both species are living in close proximity. Hybrids have been found in North America; however, there are no records of hybrids in the Great Lakes (Reznicek et al. 2011).

In its native range, European water horehound is a common, widespread species that can dominate some ecosystems (Lucassen et al. 2006, van der Valk and Verhoeven 1988). A majority of seeds collected during a survey of moving bodies of water in the Netherlands were from L. europaeus. This species also had the highest germination rate of all the seeds collected (Boedeltje et al. 2003).

Stammel et al. (2003) report that L. europaeus possess a chemical compound that may be effective against herbivores in the Great Lakes.

There is little or no evidence to support that Lycopus europaeus has significant socio-economic impacts in the Great Lakes.
Lycopus europaeus can be found in brick and concrete wall structures in urban environments (Francis and Hoggart 2011). Over time these structures could weaken.

There is little or no evidence to support that Lycopus europaeus has significant beneficial effects in the Great Lakes.
Historically, L. europaeus has been used as an astringent, cosmetic, douche, narcotic, refrigerant, and to treat fever, sores, and wounds.

Six isopimarane diterpeniods, which are compounds frequently used in pharmaceuticals, have been isolated from L. europaeus (Hussein et al. 1999). A diterpenoid isolated from L. europaeus, euroabienol, showed activity against 15 strains of bacteria and 6 fungal strains. Euroabienol has great potential to be used as a broad spectrum antibiotic and/or antifungal (Radulovic et al. 2010). Gibbons et al. (2003) found that diterpenes from L. europaeus, when combined with other compounds, have potential at regulating bacteria that have resistance to multiple drugs.

Polar extracts from L. europaeus contain flavonoids and phenolic acids; both of which are antioxidants (López et al. 2007). Another polyphenolic compound extracted exhibits the potential to influence the thyroid glands and gonads (Fecka and Cisowski 1999). Mild forms hyperthyroidism can be improved by taking extracts from L. europaeus (Beer et al. 2008, Wojciechowski et al. 2003). Patients who were given low doses of L. europaeus experienced reduced levels of thyroid hormone and reduced cardiac symptoms (Vonhoff et al. 2006).

Management: Regulations (pertaining to the Great Lakes)

There are no known regulations for this species.

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

There are no known biological control methods.

There are no known physical control methods.

There are no known chemical control methods.

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.

References: (click for full references)

Beer, A.M., K.R. Wiebelitz, and K. Schmidt-Gayk. 2008. Lycopus europaeus (gypsywort): effects on the thyroidal parameters and symptoms associate with thyroid function. Phytomedicine 15(1—2): 16—22.

Boedeltje, G., J.P. Bakker, R.M. Bekker, J.M. van Groenendael, and M. Soesbergen. 2003. Plant dispersal in a lowland stream in relation to occurrence and three specific life-history traits of the species in the species pool. Journal of Ecology 91: 855—866.

Brändel, M. 2006. Effect of temperatures on dormancy and germination in three species in the Lamiaceae occurring in northern wetlands. Wetlands Ecology and Management 14: 11—28.

Cosyns, E., S. Claerbout, I. Lamoot, and M. Hoffmann. 2005. Endozoochorous seed dispersal by cattle and horse in a spatially heterogeneous landscape. Plant Ecology 178(2): 149 — 162.

Fecka, I., and W. Cisowski. 1999. Multiple gradient development TLC in analysis of complex phenolic acids from Lycopus europaeus L. Chromatographia 49(5/6): 256—260.

Francis, R.A., and S.P.G. Hoggart. 2011. The flora of urban river wallscapes. River Research and Applications: 1—17.

Gibbons, S., M. Oluwatuyi, N.C. Veitch, and A.L. Gray. 2003. Bacterial resistance modifying agents from Lycopus europaeus. Phytochemistry 62(1): 83—87.

Hussein, A.A., B. Rodríguez, M. de la Paz Martínez-Alcázar, and F.H. Cano. 1999. Diterpenoids from Lycopus europaeus and Nepeta septemcrenata: Revised structures and new isopimarane derivatives. Tetrahedron 55(23): 7375—7388.

Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.  

López, V., S. Akerreta, E. Casanova, J.M. García-Mina, R.Y. Cavero, and M.I. Calvo. 2007. In vitro antioxidant and anti-rhizopus activities of Lamiaceae herbal extracts. Plant Foods for Human Nutrition 62: 151—155.

Lucassen, E.C.H.E.T., A.J.P. Smolders, G. Boedeltje, P.J.J. van den Munckhof, and J.G.M. Roelofs. 2006. Groundwater input affecting plant distribution by controlling ammonium and iron availability. Journal of Vegetation Science 17: 425—434.

NatureServe. 2008. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.0. NatureServe, Arlington, Virginia. Available Accessed 24 July 2008.

Old Woman Creek National Estuarine Research Reserve (OWC NERR). 2011. Old Woman Creek National Estuarine Research Reserve Management Plant 2011—2016. Advisory Council of the Old Woman Creek National Estuarine Research Reserve. 504 pp. Available

Online Atlas of the British & Irish Flora. 2012. Lycopus europaeus (Gipsywort). Botanical Society of the British Isles, Biological Records Centre, Joint Nature Conservation Committee, Centre for Ecology & Hydrology. Available Accessed 14 September 2012.

Percival, M. 1947. Pollen collection by Aphis mellifera. New Phytologist 46(1): 142—165.

Plant For A Future. 2008. 

Radulovic, N., M. Denic, and Z. Stojanovic-Radic. 2010. Antimicrobial phenolic abietane diterpene from Lycopus europaeus L. (Lamiaceae). Bioorganic & Medicinal Chemistry Letters 20(17): 4988—4991.

Reznicek, A.A., E.G. Voss, and B.S. Walters. 2011. Michigan Flora Online. University of Michigan. Available Accessed 6 Septemeber 2012.

Soons, M.B., C. van der Vlugt, B. van Lith, G.W. Heil, and M. Klaassen. 2008. Small seed size increase the potential for dispersal of wetland plants by ducks. Journal of Ecology 96: 619—627.

Stammel, B., K. Kiehl, and J. Pfadenhauer. 2003. Alternative management on fens: Response of vegetation to grazing and mowing. Applied Vegetation Science 6:245—254. 

United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS). 2012. PLANTS Database. Threatened & Endangered. Available Accessed 23 July 2012.

U.S. Environmental Protection Agency (USEPA). 2008. Predicting future introductions of nonindigenous species to the Great Lakes. Washington DC. 138 pp.

van den Broek, T., R. van Diggelen, and R. Bobbink. 2005. Variation in seed buoyancy of species in wetland ecosystems with different flooding dynamic. Journal of Vegetation Science 16: 579—586.

van der Valk, A.G. and J.T.A. Verhoeven. 1988. Potential role of seed banks and understory species in restoring quaking fens from floating forests. Vegetatio 76(1/2): 3—13.

Vogt, K., L. Rasran, and K. Jensen. 2006. Seed deposition in drift lines during an extreme flooding event- Evidence for hydrochorous dispersal? Basic and Applied Ecology 7(5): 422—432.

Vonhoff, C., A. Baumgertner, M. Hegger, B. Korte, A. Biller, and H. Winterhoff. 2006. Extract of Lycopus europaeus L. reduces cardiac signs of hyperthyroidism in rats. Life Sciences 78(10): 1063—1070.

Wojciechowski, H., H.G. Gumbinger, U. Vahlensieck, H. Winterhoff, A. Nahrstedt, and F.H. Kemper. 2003. Analysis of the components of Lycopus europaeus L. in body fluids during metabolism studies comparison of capillary electrophoresis and high-performance liquid chromatography. Phytochemistry 62(1): 83—87.

Zinck, M. and A.E. Roland. 1998. Roland's Flora of Nova Scotia; rev. M. Zinck; 2 Vol. 3rd edition.

Author: Cao, L., and L. Berent.

Contributing Agencies:

Revision Date: 9/23/2012

Citation for this information:
Cao, L., and L. Berent., 2022, Lycopus europaeus L.: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI,, Revision Date: 9/23/2012, Access Date: 8/11/2022

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.