About Lysimachia nummularia L.
Lysimachia nummularia L. is a vigorous, prostrate evergreen perennial. It reaches 5 cm (2 in) in height and spreads rapidly and indefinitely through stem-rooting. It bears rounded leaves arranged in opposite pairs, and produces 2 cm diameter cup-shaped yellow flowers during summer. This species is especially associated with damp or wet areas, though cultivated plants tolerate drier growing conditions. It is hardy, surviving temperatures as low as −15 °C (5 °F), matching RHS hardiness rating H5. It is native to Europe, but has been introduced to North America, where it is classified as an invasive species in some regions. It spreads aggressively in favorable conditions, including on low wet ground or near ponds. The species can be removed by hand weeding if all stems and stem fragments are taken out, which prevents leftover stems from rooting and regrowing. The cultivated cultivar 'Aurea', commonly called golden creeping Jenny, has yellow foliage and grows somewhat less aggressively than the wild species. This cultivar is grown as an ornamental plant, used as groundcover in locations where the spread of its growth can be restricted. It is also well-suited for use in bog gardens or as an aquatic marginal plant. It has been awarded the Royal Horticultural Society's Award of Garden Merit.
