Lycopus lucidus auct. non Turcz. ex Benth., Lycopus lucidus spp. americanus (A. Gray) Hultén, Lycopus lucidus var. americanus A. Gray, rough water-horehound, rough bugleweed

The inflorescence is a tight cluster of small, white, stalkless flowers (Glen 2012). Pairs of clusters in opposite leaf axils form false whorls on the upper 2/3 of the stem (Valo 2012). There are 5 white corolla (petals) that unite at the base into a tube, then separate at the tip into 4 lobes. The corolla is slightly longer than the calyx. There are 2 fertile stamens with brown anthers and 2 sterile stamens (staminodes). The stamens and the style are longer than corolla tube. The staminodes are club-like and are shorter than the corolla tube. The flowers not have a fragrance (Valo 2012).
Calyx lobes consist of 5 green narrow sepals (the outer whorl of protective leaves of a flower) are united for most of their 4mm length, bell-shaped tube with 5 teeth (Glen 2012). The calyx teeth are 1⁄16 cm to ? cm long, firm, and awl-shaped (Valo 2012).

The fruit is a set of 4 egg-shaped, brown, hairless, ridged nutlets with one seed each. The center of the nutlets is depressed. When the fruit is mature the calyx lobes distinctly surpass the mature nutlets. The ridges on the nutlets are corky, aiding dispersal by allowing the nut to float on water (Valo 2012).

Below ground L. asper has long, slender, horizontal rhizomes and fibrous roots. The rhizome has a tuber at the tip from which next year’s stem will rise. It does not produce stolons (above-ground runners) (Valo 2012).

Lycopus asper is very similar in appearance to the native L. virginicus (USDA NRCS 2012). As noted above, L. asper has narrow, acutely pointed lobes of its sepals (outer floral ring), while L. virginicus has sepals that are ovate and blunt (Glen 2012).

First Great Lakes record: Lake Erie, 1892 (USEPA 2008).

Lycopus asper flowers bloom from July-August, with seeds dispersing shortly afterward (Godfread 2004). Its seeds are buoyant and can be transported via waterways and irrigation canals (Valo 2012). Approximately 50% of the seeds collected were capable of germination (Kelley and Bruns 1975).

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

Environmental

Current research on the environmental impact of Lycopus asper in the Great Lakes is inadequate to support proper assessment.
Realized:
Lycopus asper is found in industrialized areas, polluted habitats, and other man made habitats. It is now frequent in the western Lake Erie area and local elsewhere in wet ground, especially disturbed shores and ditches (Reznicek et al. 2011). In a survey of fens in Ohio, Lycopus spp. constituted less than 2% of vegetation cover (Barry et al. 2008).

Potential:
Lycopus asper could pose a competitive threat to native species, including L. americanus Muhl. ex W. Bartram, L. amplectens Raf., L. rubellus Moench, L. uniflorus Michx., and L. virginicus L. (USDA NRCS 2012).

There is little or no evidence to support that Lycopus asper has significant socio-economic impacts in the Great Lakes.

There is little or no evidence to support that Lycopus asper has significant beneficial effects in 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.

Control
Biological
There are no known biological control methods.

Physical
There are no known physical control methods.

Control
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.