1. Lycopus americanus Muhl. ex W.P.C. Barton (American bugleweed)

L. americanus var. longii Benner

L. americanus var. scabrifolius Fernald

Pl. 435 f; Map 1956

Plants with elongate rhizomes, but lacking tubers and usually not producing stolons. Stems 30–90 cm long, bluntly or sharply 4-angled, the faces flat or more commonly shallowly concave to grooved, glabrous or sparsely to densely pubescent with short, appressed and/or longer, spreading hairs. Leaf blades 1.5–15.0 cm long, very variable, narrowly ovate to narrowly lanceolate, narrowly elliptic, or 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, usually to a winged, petiolar base, tapered to a sharply pointed tip (or lobe tips), the upper surface glabrous, the undersurface glabrous or sparsely short-hairy along the veins. Bractlets 1–3 mm long, narrowly lanceolate to elliptic-lanceolate. Calyces 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. 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. 2n=22. June–October.

Scattered throughout the state (throughout the U.S.; Canada, possibly also Asia; introduced rarely in South America). Bottomland forests, sloughs, oxbows, banks of streams and rivers, margins of ponds, lakes, and sinkhole ponds, fens, bottomland prairies, moist swales of upland prairies, and bases and ledges of bluffs; also ditches, fallow fields, railroads, roadsides, and moist disturbed areas.

This is the most common and widespread species of Lycopus in the state. Steyermark (1963) segregated somewhat hairier plants as var. longii and mentioned plants with somewhat roughened leaves as possibly representing var. scabrifolius, but Henderson (1962) concluded that the species is best treated as a single variable taxon.