Lesser celandine ( Ranunculus ficaria), also called fig buttercup, is a native of Europe and North Africa that was brought to North America as a garden ornamental but escaped cultivation. It can invade moist woodlands and crowd out native wildflowers. Lesser celandine can form a dense carpet in early spring, preventing native plants from sprouting. While it dies back by June, its network of roots and tubers remains to inhibit other plants.
The dark-green leaves are shiny, up to 1.5 inches long, and heart- to kidney-shaped. The plants grow less than 1 foot high, with bright-yellow flowers about an inch in diameter, usually with eight petals.
Small infestations can be controlled by digging, taking care to remove as much of the plant as possible above and below ground. The Whatcom County Noxious Weed Control Board can provide advice about chemical treatments.