This commonly cultivated perennial ("yellow archangel") can persist from gardens or garden waste, and it is locally escaped in humid mid-temperate regions of North America (K). It is well established in urban woodlands of JEFF, being locally common and invasive at Iroquois Park, and a with few patches at Cherokee Park (colls. of P. Haragan for EKY). And Brock (2020; APSC) has discovered it along a road adjacent to lowland woods in TODD. All plants in Ky. may be referable to the cultivar "variegatum", which has been classified within ssp. argentatum (Smejkal) Stace. This cultivar is not known to produce seeds, but it has aggressive stolons (Rotherham 2005). Ssp. argentatum was described in 1975 but has then rapidly spread into Britain from Europe (brc.ac.uk/plantatlas). It is also becoming an invasive problem in the Pacific Northwest (Miller et al. 2014). These plants have sometimes (including from JEFF) been misidentified as Lamium maculatum L., which is also perennial but with larger purplish flowers. The latter is another popular plant in gardens (especially the "spotted" cultivar with variegated leaves); it is naturalized locally in humid cool-temperate regions of North America (K, W), and expected in Ky.