Contact: Wesley Knapp, Maryland Department of Natural Resources | WKnapp@dnr.state.md.us
ANNAPOLIS, MD (April 9, 2012) – What is that beautiful lush green vegetation growing all along over that floodplain with pretty yellow flowers? That is the incredibly invasive lesser celandine (Ficaria verna). Also known as the fig buttercup, this pretty yellow flowering plant now dominates the floodplains of many forested streams of central Maryland loving the rich soils and heavy shaded habitats they provide. For this reason the Maryland Invasive Species Council has selected lesser celandine as April’s Invader of the Month.
The lesser celandine occurs in such abundance that it out-competes and crowds out other competing vegetation. Above ground you can see the dense green carpet of vegetation that blankets the soil surface, but parts you can’t see are just as detrimental to other vegetation. This plant produces an abundance of below ground tubers (bulbous roots) that occupy and compete with other vegetation. These tubers look like small fingerlike projections off the roots and are easily visible when the plants are uprooted. Though the lesser celandine is an ephemeral plant, meaning the above ground vegetation disappears by summer, the belowground tubers are ever present. This creates year-round competition for root space with all types of plants not just spring wildflowers.
The lesser celandine is a native of Europe, Northern Africa and Western Asia and was introduced to the United States sometime in the 1700th centaury as a horticultural plant. It is still available through cultivation in many different varieties and colors. Scientists currently recognized five subspecies of the fig buttercup that have become widespread and established in the United States. Four of these subspecies are known from Maryland and all are believed to be invasive. These subspecies are ssp. calthifolia, chrysocephala, fertilis, and verna. These subspecies area all very similar and can be difficult to identify. If you are interested in these different subspecies examine a recent technical botanical text.
The fig buttercup is a small perennial herbaceous plant with a maximum height of up to about 10 inches. The yellow attractive flowers are about 3 inches across and come into bloom in very late winter and the earlier portion of the spring. After flowering, the basal round leaves carpet the forest floor until the mid-summer. The basal leaf is sometime speckled with a darker green towards the center of the leaf in contrast to the lighter green of the leaf edge. The thick tuberous roots for a dense network below the soil surface and can attain a size of about half an inch.
Controlling this plant is difficult and typically involves chemicals. Manual or mechanical removal of small infestations can be successful but removing all the below ground parts is critical. If mechanical control is used all parts need to be bagged and removed from the site. This plant can and readily reproduces through vegetative means meaning any missed roots can produce new plants. Chemical controls should be used during the active growing and blooming period, between February-March. Spraying during this time period prevents killing other native plants in the vicinity as most haven’t emerged yet. Typically Rodeo is used because it is usable in wetland situations. It usually takes more than one year worth of chemical treatments to control the infestations.
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For more information about Invasive Species of Concern in Maryland, visit www.mdinvasives.org