5. Lycopus virginicus L. (bugleweed, Virginia bugleweed)

Pl. 435 j, k; Map 1960

Plants with elongate rhizomes, also producing slender stolons, these rarely with small tubers at the tips. Stems 30–90 cm long, bluntly 4-angled, the faces flat or very shallowly concave to grooved, moderately pubescent with short, appressed-ascending hairs, sometimes also with sparse longer, multicellular hairs. Leaf blades 1–10 cm long, lanceolate to ovate or elliptic, unlobed, the margins coarsely and sharply toothed, tapered concavely to a sometimes short, winged petiolar base, tapered to a sharply pointed tip, the upper surface glabrous or sparsely short-hairy along the midvein, the undersurface glabrous or more commonly sparsely to moderately short-hairy only along the veins. Bractlets 0.5–1.0 mm long, linear. Calyces 1–2 mm long, 4-lobed from less than to less commonly about the midpoint, the lobes ascending to somewhat spreading, triangular to broadly triangular, rounded or more commonly angled to a bluntly pointed tip. Corollas 1.8–2.2 mm long, 4-lobed, the upper lobe often shallowly notched at the tip, all of the lobes ascending. Stamens not exserted. Nutlets 1.6–2.0 mm long, extending beyond the calyx tube at maturity, noticeably oblique at the tip, the corky band with 4–6 blunt teeth or tubercles along the nutlet apex. 2n=22. August–October.

Scattered nearly throughout the state (eastern U.S. west to Minnesota and Texas; Canada). Bottomland forests, swamps, sloughs, oxbows, banks of streams, rivers, and spring branches, margins of ponds, lakes, and sinkhole ponds, bottomland prairies, and bases and ledges of bluffs; also ditches, railroads, and moist disturbed areas.

An uncommon hybrid between L. virginicus and L. uniflorus (L. ×sherardii E.S. Steele) occurs where these species grow in proximity. It has been reported from the eastern Great Plains (including Kansas and Iowa) eastward and thus might eventually be discovered in Missouri. Hybrids tend to have the appearance of L. virginicus but are intermediate between the putative parents for corolla and nutlet characters.