This introduced perennial plant is 2-5' tall and sparingly branched below the inflorescence. The stems are 4-angled, heavily ridged, and slightly pubescent. The opposite leaves are variable in size and shape, although they all have long petioles that are slightly pubescent. The lower leaves often have 5 cleft lobes and several coarse teeth; they are up up to 4" long and 3" across. The middle leaves have 3 cleft lobes and a few coarse teeth; they are up to 3" long and 1½" across. The upper leaves are often oblong-ovate with a pair of coarse teeth; they are up to 2" long and ¾" across. These leaves are nearly hairless and have conspicuous veins along the upper surface. The base of each leaf is more or less wedge-shaped. The stems of Motherwort are normally erect, although older plants toward the end of the growing season have a tendency to sprawl. Whorls of sessile flowers occur above the axils of the opposite leaves on the middle to upper stems. Each tubular flower is 2-lipped and about 1/3" long. The corolla is white or light pink and quite hairy on the upper side; these fuzzy white hairs exceed 1 mm. in length. The upper lip is undivided, while the lower lip has a central lobe and 2 smaller side lobes. There are usually purple dots on the lower lip and near the throat of the corolla. The tubular green calyx has 5 lanceolate teeth; it is slightly pubescent. These teeth are sharp-pointed and persistent. The blooming period occurs during the summer and lasts about 2 months. While the flowers are not noticeably fragrant, the foliage has a slightly rank odor. Each flower is replaced by 4 nutlets that are 3-sided and reddish brown or brown. The root system consists of shallow fibrous roots and rhizomes. This plant spreads by reseeding itself and vegetatively by means of the rhizomes; it often forms colonies.
Leonurus cardiaca Cultivation - Angelfire, http://www.angelfire.com/me/absent/plants/leonuruscardiaca.html (accessed January 24, 2017).