All of my specimens except one are from the lake area. The Parke County specimen was found east of Rosedale, in "Nigger Legs" prairie, which is now drained. It is frequent throughout the lake area and usually common where found. It grows mostly on the borders of lakes in the moist, sandy or marly shores. I have seen this species common in the litter on the shore of a lake, while in a zone back of the litter, Lycopus virginicus was found; but the two species were restricted to two separate zones. it is also found in marshes, sphagnum bogs, and mucky places. The tuber on this species has always interested me, and a few years ago I planted one year old seedlings with a tuber and the second year I found that the tuber had decayed and, in clay soil, the plant was, as usual, stoloniferous with many subterranean tubers. Two year old plants were planted in clay, and they were more proliferous and grew an incredible number of tubers. The limited number of tubers in their native habitat is doubtless due to lack of nutrients. This species is not satisfactorily separated from the next one [Lycopus virginicus] and more study is needed on all parts, especially on the flowers.
Plants stoloniferous, each stolon ending in a shallow tuber from which the solitary stem arises the next year; herbage inconspicuously hairy or glabrous; lvs lanceolate or oblong, 2-6 cm, acute or short-acuminate, with a few low teeth, the proximal margins straight or slightly convex, rarely slightly concave; cal-lobes 5; cor 5-lobed, the lobes ±spreading; stamens exsert; nutlets surpassing the cal, each 1.1-1.8 mm, three-fourths as wide, the tubercles commonly 3 and restricted to the peripheral margin, the interior angle distinctly shorter than the outer ones and not ending in a tubercle, the set of 4 nutlets therefore with a depressed center; 2n=22. Nf. and e. Que. to Alas., s. to N.C., Ark., and Calif. (L. virginicus var. pauciflorus)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.