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

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).

Summary of species impacts derived from literature review. Click on an icon to find out more...

Environmental	Socioeconomic	Beneficial

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

Realized:
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).

Potential:
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.
Potential:
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.
Realized:
Historically, L. europaeus has been used as an astringent, cosmetic, douche, narcotic, refrigerant, and to treat fever, sores, and wounds.

Potential:
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).

There are no known regulations for this species.

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

Control
Biological
There are no known biological control methods.

Physical
There are no known physical control methods.

Chemical
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.