We have been working hard to remove the invasive plant, Lesser Celandine, from parks near the College Park Sierra Club office, including Magruder Woods, Cherry Hill Park, and Little Paint Branch Park. Local community service volunteers, our stewardship intern, and park rangers have been hand-removing these plants with shovels to get the bulbs out.
Anatomy of Lesser Celandine
Lesser Celandine, Ranunculus ficaria L., also known as Fig Buttercup, is an herbaceous, flowering, perennial plant native to Europe. It was brought to the United States as an ornamental plant. It can be identified by its glossy, dark green, kidney-shaped leaves with its bright yellow flowers blooming in early spring. It spreads using its finger-like tuberous roots and blooms from March through April. Caltha palustris, a.k.a. Marsh marigold, is a native plant that looks very similar to Lesser Celandine. This look-alike tends to grow in much wetter, marshy habitats, and forms in clumps rather than spreading out across the ground. Another way to tell the two apart is that Lesser Celandine typically has 7-12 petals, while Marsh Marigold has 5-9. Be sure that the plant you are looking at is indeed Lesser Celandine before attempting to remove it.
Marsh Marigold, a native look-alike to Lesser Celandine
Lesser Celandine is invasive in 22 states and parts of Canada. It arrives early in the spring, spreading out over the ground, creating a thick carpet, making it virtually impossible for native understory plants to grow and survive there. Native wildflowers are particularly negatively impacted by this invasive species. Lesser Celandine prefers partially shaded areas, but is capable of growing in direct sunlight if it has adequate soil moisture.
Map of Lesser Celandine’s invasive range in the United States and Canada
From https://plants.usda.gov/core/profile?symbol=RAFI
It can easily escape from private plantings and grow quickly in the wild. Management can be difficult because of the bulbous nature of the plant’s root system. Manual control can lead to bulb fragments being left behind, causing reinfestation. If you are removing plants manually, be sure to put all parts of the plant in a sealed bag and do not attempt to compost it, as this will cause it to continue to spread. Chemical control is possible if timed properly and applied correctly. However, some herbicides are non-selective in nature which can lead non-target species being negatively affected. There are currently no biological controls approved for this species, so more research must be done in order to develop working forms. One action you can take is to request that your federal legislators allocate funding for a pathogen quarantine facility for research on effective, host-specific, biological control of Lesser Celandine.
Map of reports of Lesser Celandine by county in Maryland
From https://www.marylandbiodiversity.com/viewSpeciesQuadMap.php?species=3034
Get outdoors
Participate in the Oxon Cove Shoreline Sweep-Up on Sunday, May 5 and/or an invasive species removal outing on Saturday, May 11! Find more invasive species removal outings and other outdoor activities on our calendar.
Works Cited:
https://extension.umd.edu/hgic/topics/lesser-celandine
https://extension.umd.edu/learn/weed-week-lesser-celandine
https://weedwise.conservationdistrict.org/rafi
https://plants.usda.gov/core/profile?symbol=RAFI
https://www.marylandbiodiversity.com/viewSpeciesQuadMap.php?species=3034
Submitted by Anna Eyler, Communications Intern Spring 2019