Coptis aspleniifolia, commonly known as Fernleaf Goldthread, is an evergreen perennial herb native to the moist, acidic soils of the understory in temperate rainforests and wet woods. It is found in the northern regions of British Columbia, Alaska, and extends down the Cascades into Washington. Fernleaf Goldthread typically grows to a modest height of 6-10 inches (15-25 cm) with a similar spread, and it features delicate, fern-like, dark-green, glossy leaves. Its pale greenish-white flowers bloom in early spring and are not particularly showy, but they add subtle interest to the woodland garden. The plant also produces small, thread-like rhizomes that are bright yellow, which is how it gets its common name.

Fernleaf Goldthread is valued for its ornamental foliage and its use as a low-maintenance ground cover in shady garden spots. It is also appreciated for its medicinal properties, as the rhizomes contain berberine, which has been used traditionally to treat various ailments. In cultivation, it prefers cool, moist conditions, and well-drained, humus-rich soil with consistent moisture. It is suitable for planting in shaded rock gardens, woodland settings, and alongside streams or ponds. While generally disease-free, it can suffer from root rot if the soil is too wet. Fernleaf Goldthread is not known to be invasive and does not have aggressive roots, making it a safe choice for cultivation in appropriate climates.CC BY-SA 4.0