Lysimachia nummularia

f9 @ 1/250s, ISO:500, Nikon D3S w 105mm macro

"Lysimachia nummularia," Wikipedia. the free encyclopedia. Lysimachia nummularia is a species of flowering plant in the family Primulaceae. Its common names include creeping jenny, moneywort, herb twopence and twopenny grass.It is native to Europe, but has been introduced to North America, where it is considered an invasive species in some areas. It aggressively spreads in favorable conditions, such as low wet ground or near ponds, but is usually easily removed by hand pulling.It is a vigorous, prostrate, evergreen perennial growing to 5 cm (2 in) in height and spreading rapidly and indefinitely by stem-rooting. It has rounded leaves, and cup-shaped yellow flowers 2 cm in diameter, in summer. It is particularly associated with damp or even wet areas, though in cultivation it will tolerate drier conditions. It is cold hardy, surviving lows of −40 F (−40 C).
Francis A. Crane Wildlife Management Area, East Falmouth, Massachusetts