A perennial from the Primulaceae family, Lysimachia ephemerum is native to the Iberian Peninsula and the southwest of France, where it grows spontaneously by streams, springs, and wet areas, in marshy meadows and riparian forests of lowland and mid-mountain regions.
It forms upright, slender, and strictly vertical clumps, reaching 60 to 90 cm in height. The stems are smooth, glaucous, bearing opposite, lanceolate leaves of a characteristic bluish-green, almost waxy appearance, giving the plant a cold and architectural elegance that is easily recognizable.
The flowers, pure white to slightly pinkish-white, are small and star-shaped, gathered in long, upright terminal spikes, graceful and dense, which persist on the plant for a long time. In its natural habitat, its flowering extends from June to August. In cultivation, it generally blooms from June to July.
It is cultivated in fresh to moist soil, even temporarily waterlogged, in full sun or partial shade. Unlike other loosestrifes, it does not have an invasive tendency, making it a particularly recommendable perennial for banks or humid beds in sober and natural gardens.