Fringed loosestrife is one of the most widespread native Lysimachia species in North America, growing across southern Canada and most of the lower 48 states from wetland margins and stream banks to moist deciduous woods and flood plains. It stands upright with minimal branching, reaching 1 to 4 feet tall depending on conditions, and produces star-shaped yellow flowers from midsummer into early fall. The flowers are unusual in offering floral oils rather than pollen as their pollinator reward, which draws specialist bees adapted to harvest them.

It thrives in full sun to light shade in wet to moist conditions, preferring loamy soil rich in organic matter. The petiole fringe that gives the species its name sets it apart from related loosestrifes and is worth examining up close. Populations are declining in some areas due to wetland loss, so planting it along a pond edge, rain garden, or boggy border contributes something beyond ornament. Some leaf-feeding insects find it attractive, though none cause lasting damage.