Lysimachia vulgaris is an herbaceous perennial with erect stems up to 3.3 ft. (1 m) in height and long, stolon-like rhizomes that can run 33 ft. (10 m) long.
Foliage
The leaves of this plant are opposite or whorled. They have small glands that are black or orange in color and soft hairs beneath. They are lanceolate to laceolate-ovate in shape, 2.75-4.75 in. (7-12 cm) in length and 0.6-1.5 in. (1.5-4 cm) in width. The middle and upper leaves have short petioles and are acuminate.
Flowers
The inflorescence is a terminal, leafy panicle that appears June-September. The flowers are have five yellow petals and are 0.5-0.75 in. (1.2-2 cm) across. The lobes of the calyx are red-margined and 0.15-0.2 in. (3.5-5 mm) long.
Fruit
The fruits are dry capsules. The seeds of this plant are most likely water-dispersed. However, the main method of dispersal for this plant is via rhizomes.
Ecological Threat
Lysimachia vulgaris presents a similar threat as the serious invasive Lythrum salicaria (purple loosestrife). In Washington state it has been reported as possibly outcompeting Lythrum salicaria in wetland habitats. The rhizomes spread readily. Though its populations have not yet reached the numbers of Lythrum salicaria populations, it has the potential to do so. Lysimachia vulgaris prefers moist soil, and will invade fens, wet woods, lake shores, rocky river shores and riparian zones.