Lycopus americanus Muhl. ex W.P.C. Barton

American Bugleweed


CC = 4
CW = -5
MOC = 89

© SRTurner

Family - Lamiaceae

Habit - Perennial forb with elongate rhizomes, lacking tubers.

Stem - Ascending to erect, to 90 cm, 4-angled, glabrous to densely pubescent with short, appressed and/or long, spreading hairs.

Lycopus_americanus_stem.jpg Stem.

© SRTurner

Leaves - Opposite, short-petiolate, the petioles wings. Blades 1.5-15.0 cm long, highly variable, narrowly ovate to narrowly lanceolate to nearly linear in outline, those of at least the lower leaves deeply pinnately lobed (the lobes entire, few toothed, or occasionally pinnately few-lobed), those of the upper and sometimes also median leaves often merely coarsely few-toothed, tapered concavely at the base, tapered to a sharply pointed tip, the upper surface glabrous, the undersurface glabrous or sparsely short-hairy along the veins.

Lycopus_americanus_leaf2.jpg Leaf abaxial.

© SRTurner


© SRTurner

Inflorescences - Dense axillary clusters, with numerous flowers per node, these sessile or nearly so. Bractlets 1-3 mm long, narrowly lanceolate to elliptic-lanceolate.

Lycopus_americanus_inflorescences.jpg Inflorescences.

© SRTurner

Flowers - Calyces nearly actinomorphic, 2.0-3.2 mm long, 5-lobed to about the midpoint, the lobes more or less spreading, narrowly triangular, tapered to a sharply pointed tip. Corollas 2.5-3.5 mm long, 4-lobed, the upper lobe slightly broader than the others and shallowly notched, the lateral and lower lobes spreading. Stamens slightly exserted.

Lycopus_americanus_calyces.jpg Calyces.

© SRTurner

Lycopus_americanus_flowers.jpg Flowers.

© SRTurner

Lycopus_americanus_flowers2.jpg Flowers2.

© SRTurner

Fruits - Nutlets 1.0-1.4 mm long, shorter than the calyx tube at maturity, more or less oblique at the tip, the corky band entire or slightly undulate, lacking teeth or tubercles.

Flowering - June - October.

Habitat - Bottomland forests, sloughs, streambanks, pond margins, ditches, fields, open wet areas.

Origin - Native to the U.S.

Lookalikes - Other species of Lycopus, also plants in the genus Mentha and Spermacoce glabra.

Other info. - This is the most common bugleweed in Missouri, being found in nearly every county in the state. It is also found in every state in the continental U.S. except Nevada, although it is less common in southern and Plains states.

The bugleweeds are easy to recognize generically, but can be very difficult to identify to the species level. They are differentiated from the culinary mints (Mentha sp.) by having sessile, rather than stalked, flowers. They also lack any trace of minty aroma. Lycopus americanus is usually recognized by having deeply lobed lower leaves, but this character is extremely variable and not very reliable. Other clues are its nutlets, which are shorter than the calyx enclosing them, and corollas with 4 lobes. The genus is taxonomically problematic and could use further study.

Photographs taken at Klondike County Park, St. Charles County, MO, 8-3-2014, and at Big Cane Conservation Area, Butler County, MO, 9-7-2019 (SRTurner).