Ranunculus ficaria

Lesser celandine is a weedy perennial groundcover in the Ranunculaceae (buttercup) family. It was introduced into North America and has naturalized in 19 states in the Northeast, the Pacific Northwest, and eastern Canada. In wild areas, plants  compete with native plants and wildflowers forming large, dense vigrous colonies that sometimes cover several acres of land. 

Flowers are easy to spot in the early spring.  After flowering, the plant foliage dies back by early summer as the plants go dormant.  Bulblets on above ground stems and underground tubers are the primary methods of propagation. Tubers resemble figs, hence the Latin name.  The spread of bulblets and tubers can be accelerated by such factors as animal digging and downstream flooding.

Insect, Disease, and Other Problems: No serious insect or disease problems. Slugs and snails may appear. When planted in a garden, plants tend to spread invasively into adjacent areas. Exercise caution in planting this perennial in the landscape. Some cultivars are reportedly less aggressive.