Leonurus cardiaca is a perennial herb, colonial from rhizomes with fibrous roots, stems to 1.5 m tall, from an overwintering basal rosette (Levine 1995; Yatskievych 2006); stems, stout, erect, branched, ribbed or strongly angled, usually clustered.
Leaves opposite, stalks to 13 cm long, blade to 15 cm long, 12 cm wide, deeply 3-lobed and toothed, lobe tips pointed, surface hairy, dull dark green, puckered from impressed veins, veins palmate at base, secondary veins netted, lower leaves broadly heart-shaped, progressively smaller and narrowed upward.
Flowers pale purple with darker spots, tubular, bilaterally symmetrical, densely hairy outside, tube to 0.6 cm long, 0.2 cm wide, petal lobes deeply 2-lipped, upper lip 0.5-0.6 cm long, lower lip small, 3-lobed, to 0.2 cm long, calyx bilaterally symmetrical with 5 sharp lobes, becoming tan, stiff and spine-tipped in fruit (Yatskievych 2006); inflorescences of dense clusters ringing stem at nodes, stems often persisting into winter; blooms June-Aug.
Fruit dry, 4-nutlets.
Wetland status: UPL.
Frequency in NYC: Infrequent.
Habitat: Open areas.
Notes: Used as an herbal medicinal.