1. Leonurus cardiaca L. (motherwort)

Pl. 435 a, b; Map 1953

Plants perennial, with fibrous roots. Stems 40–150(–200) cm long, glabrous or sparsely pubescent with short, fine, downward-angled hairs, often mostly on the angles. Leaf blades 1–12 cm long, those of the lower leaves palmately (3–)5–9 lobed and broadly ovate to nearly circular in outline, grading into those of the median and upper leaves, which are unlobed or 3-lobed and ovate to elliptic in outline, the margins otherwise with few, coarse, sharp teeth, variously rounded to narrowly angled or tapered at the base, angled or tapered to a sharply pointed tip (or lobe tips), the upper surface glabrous or sparsely to moderately pubescent with short, stiff, loosely appressed hairs near the margins, the undersurface sparsely to moderately pubescent with fine, loosely appressed hairs, mostly along the veins. Calyces 3.5–8.0 mm long, strongly 5-nerved, the nerves thickened into ribs, the teeth about as long as the tube, glabrous or sparsely and minutely hairy, also usually with numerous minute, club-shaped glands. Corollas 8–12 mm long, distinctly longer than the calyces, white to pale pink (the lower lip with reddish purple spots or mottling), moderately short-hairy externally, but the upper lip densely pubescent with longer, spreading hairs. Stamens with the anther sacs parallel. Nutlets 1.7–2.3 mm long, truncate at the tip. 2n=18. May–August.

Introduced, scattered nearly throughout the state but apparently more abundant in the western half and absent from the Mississippi Lowlands Division (native of Europe, Asia; introduced widely in the New World). Bottomland forests, openings and edges of mesic upland forests, banks of rivers, marshes, ledges and tops of bluffs; also pastures, margins of crop fields, ditches, gardens, railroads, roadsides, and open disturbed areas.

Steyermark (1963) mentioned that the young foliage can be cooked or (in limited quantities) eaten fresh, and that the dried plants were sometimes used medicinally in tonics and as a menstrual aid. He noted that exposure to the plants caused dermatitis in some individuals and that the spinescent calyces sometimes caused mechanical injuries to the soft mouth-parts of livestock. The species also is the source of a green dye.