Lesser Celandine (Ficaria verna), also known as fig buttercup or pilewort, is a spring ephemeral plant with glossy dark green leaves and bright yellow flowers. While beautiful in the spring, it is also an aggressive spreader that will quickly take over your gardens. Native to Europe and parts of Africa and Asia, it was introduced to the U.S. in the late 1860’s as an ornamental. Without diseases or predators to keep it in check, it continually outcompeted native plants and became invasive. It thrives in moist and somewhat shady areas, where it quickly spreads and forms a dense mat. Although the plant goes dormant in June, its dense growth habit crowds out native spring ephemerals and other native plants that are not strong enough to compete against it.
If you suspect that you have this plant on your property, you should remove it as quickly as possible. Small infestations of lesser celandine can be controlled by hand digging, removing its underground tubers and all other plant material. Widespread patches of the plant may require application of an herbicide such as glyphosate, which unfortunately impacts other plants.
Care should be taken not to confuse Lesser Celandine with Marsh Marigold (Caltha palustris) which is a beneficial native plant! While the two plants look similar, one difference is that Marsh Marigold tends to grow in small isolated clumps while Lesser Celandine spreads into a thick mat. There are also differences in the size of the leaves and the number of petals that their flowers have.
For more information on Lesser Celandine, how to control or eradicate it, or on how to tell it apart from Marsh Marigold, check out this resource from Ohio State.