The yellow buttercup, also known as the fig buttercup or lesser celandine, has become a threat to woodland habitats in the northern United States and southern Canada. The perennial, scientifically known as ranunculus ficaria, is native to Europe and was introduced to North America as an ornamental plant. Nurseries continue to market the buttercup as a desirable, hardy, border plant prized for its early spring flowers. Unfortunately, the buttercup easily escapes garden cultivation and threatens native ephemerals in moist woodland habitats.
Purposefully cultivated buttercups are easy to grow for the home garden or landscape and produce dense, compact plantings sporting yellow flowers under sunny conditions from March through May. Buttercups reproduce themselves through seed and vegetatively through tuberous roots that spread rapidly. What began as a seemingly benign garden species is now listed as an invasive plant because the buttercup crowds out native woodland plants and competes with domestic early spring wildflowers.
Wild buttercups tolerate dry conditions but prefer wetter, spring weather. The plants are common in mixed deciduous forests with alkaline soil. Flowers are solitary on each stem and grow to a little less than one inch in diameter. Three to four green sepals fall off early, giving way to 8 to 12 yellow petals that fade to white before dropping off. Flowering is more likely on buttercups with large tubers, and woodland flowers appear before the trees above them are in full leaf.
The buttercup is a non-native species that is quick to dominate the woodland ecosystem and eliminate native wildflowers such as marsh marigold and trilliums. Biodiversity in natural and seminatural areas is thereby seriously threatened. When buttercups grow where they are not wanted, the common garden species becomes classified as an invasive weed. Land managers must eliminate buttercups quickly, as their appearance on the scene is ephemeral or brief.
Buttercup Versus Marsh Marigold
The buttercup is sometimes confused with a native North American wild flower -- the marsh marigold. Both plants sport bright yellow flowers but the marsh marigold or Caltha palustris has multiple flowers per stem, hollow stems and larger, lighter- coloured leaves. The marsh marigold is not a spreading threat, as it reproduces by seed only. Both the buttercup and marsh marigold flower in early spring and thrive in wet woodlands.