creeping yellow loosestrife, creeping Jenny Lysimachianummularia L.
Appearance
Lysimachia nummularia is an herbaceous, low-growing, perennial plant in the primrose family. The smooth creeping stems branch frequently and can grow up to 2 ft (m) long and 2-4 in (5.1-10.2 cm) tall. It is native to temperate Asia and to Europe.
Foliage
The leaves are opposite, simple and broadly ovate 0.25-1.5 in (0.6-3.8 cm) long with entire margins. The leaves are obtuse at both ends, resembling coins and giving it the common name, moneywort.
Flowers
This plant often does not flower at all. But when it does the flowers are yellow with small dark red spots. The flowers arise from the leaf axils and have pedicels about 0.25-1.5 in (0.6-3.8 cm) long. It blooms from June to August.
Fruit
Fruit are capsules which contain 1-5 seeds each. The seeds are small.
Ecological Threat
Lysimachia nummularia can be found in a variety of different habitat types; however, it grows most vigorously and poses the biggest threat in moist areas such as wet meadows, swamps, floodplain forests, stream banks, bottoms, ditches, roadsides and along the banks of small water bodies. It can form a mat-like growth capable of excluding more desirable native plant species. It is now found across the United States and Canada.