Lysimachia nummularia is a perennial herb, creeping, mat-forming, rooting at nodes.
Leaves opposite, semi-evergreen, stalks 0.1-0.5 cm long (Radford et al. 1968), blade 1-2.5 cm long, rounded to broadly heart-shaped, surface sprinkled with tiny depressed dots.
Flowers yellow, dotted with dark red, radially symmetrical, 2-3 cm wide, petal lobes 1-1.5 cm long, calyx lobes leaf-like to 0.8 cm long, sharply keeled, appearing winged in bud (Connecticut Wildflowers 2007); flowers solitary in leaf axils, stalks as long as leaves; blooms June-Aug.
Wetland status: OBL.
Frequency in NYC: Very infrequent.
Habitat: Escaped from cultivation into moist sites; soil pH 5.6-7.5 (Dave’s Garden 2007). Tolerant of shade.
Notes: Has been used as a medicinal (Hough 1983). Listed as a noxious weed in CT and MA (USDA, NRCS 2006).Escaped plants often not blooming (Yatskievych 2006).