Lesser Celandine

Many people look forward to seeing the first flowers emerge in spring, and there are indeed many lovely plants appearing this time of year. However, spring is also the time to be on the lookout for a nasty invader: lesser celandine (Ficaria verna) (synonym=Ranunculus ficaria), also called 'fig buttercup.'

Background

A member of the buttercup family (Ranunculaceae), lesser celandine is a spring ephemeral, meaning it emerges early in spring before trees leaf out, but it doesn't stick around very long. The leaves and flowers of spring ephemeral plants are generally gone by late May in Pennsylvania, but their underground parts continue to store nutrients for re-emergence the following spring. Native to parts of Europe, Asia, and northern Africa, lesser celandine was introduced to North America as an ornamental during the 1800s and has become widespread in the northeastern and mid-western United States.

While it has been used as an ornamental for many years, it is now illegal to sell or intentionally plant lesser celandine in Pennsylvania because it has been added to the PA Noxious Weed List.

Description

Size

A low-growing plant with leaves up to 4 inches high, and flower stalks up to 9 inches long.

Leaves

Glossy and kidney-shaped, mostly smooth edges with some gentle lobes or slightly 'scalloped' appearance. No hairs. Spidery veins angle from center to outer edge. Variable in size, new plants often appear as 1-2 tiny leaves (1/4 inch wide) emerging from soil. Some cultivars exist with variegated leaves.

Flowers

Bright yellow with 8 or more narrow petals, somewhat star-shaped. Typically has a darker yellow ring in the center.

Fruit

Reproduces and spreads mainly through tubers (underground, fleshy structures, like tiny potatoes), bulblets (tiny bulb-like structures that grow on the stems), and, to some extent, seeds (depending on subspecies).

Stems

Fleshy, thin, weak, and light-green or pale white, resembling bean sprouts, especially near the base.

Dispersal

Lesser celandine can spread through movement of its seed as well as bulblets that become dislodged from the parent plant. Often, the seeds and bulblets are moved in flowing water, but can also be moved by people or animals walking through a celandine patch, or movement of vehicles and equipment. Celandine can be moved from one lawn to another on landscaping equipment. Spread can also occur if soil containing pieces of the underground tubers is moved from the site.

These multiple reproduction methods help lesser celandine become an aggressive spreader and form a dense carpet that covers large areas if left unchecked. These infestations can inhibit or prevent the growth of native plants, especially native spring ephemerals such as spring beauty (Claytonia virginica), Dutchman's breeches (Dicentra cucullaria), squirrel corn (Dicentra canadensis), and others.

Site

Lesser celandine thrives in moist, rich soil and is most prevalent in floodplains and riparian areas where flowing water helps spread the plant. It will also invade forest floors, especially in rich bottomlands, but can also spread up to higher ground. Lesser celandine will readily invade lawns and gardens.

Look-Alikes

When looking for lesser celandine, be careful to not confuse it with marsh marigold (Caltha palustris), a charming native that looks very similar to lesser celandine. To tell them apart when no flowers are present, look closely at the leaves, the edges of which are usually smooth or gently lobed on lesser celandine, but finely toothed on marsh marigold, particularly near the base. The stems of marsh marigold tend to be more robust, upright, and taller than celandine, which has thinner stems that are more limp.

When present, the flowers are easily differentiated, as lesser celandine usually has 8-12 narrow petals, while marsh marigold generally has 5 to 9 wider petals that are more rounded. Additionally, though it can sometimes form dense patches, marsh marigold typically grows individually, and it will only be found in very moist locations, like wetlands and stream banks or lakeshores. If the plant is growing in a drier site, like an upland slope or a lawn, it is not marsh marigold.

Another plant group that can be confused with lesser celandine, particularly when not in flower, is wild violet (Viola spp.). The leaves of wild violets grow in clusters close to the ground and some violets can form dense, widely spreading patches in the right conditions. At first glance, the leaves can look very similar to lesser celandine, but a closer look will show that violet leaves are toothed around the entire edge. Violet leaves also tend to have more texture, with deeper veins that curve more toward the tip. The flowers of many violets will be easily distinguished from celandine by their color, which is purple/blue or white on most violets. Yellow-flowered violet species do occur in the same range as lesser celandine, but can be readily identified by their distinctive, 5-petaled, asymmetrical shape.

Control

While it might theoretically be feasible to remove individual plants or very small patches of lesser celandine by digging them up, this removal method is not recommended as it is very difficult to get all the tubers and generally requires removing excessive amounts of soil. If you do try this method, all plant parts must be sealed in a bag for burning or disposal in the trash.

The most efficient and effective control method, and the only feasible one for most infestations, is to spray the plants with herbicide. The recommended active ingredient for lesser celandine control is glyphosate. This is a systemic herbicide, meaning it will be absorbed by the leaves and stems and will move within the plant to control all parts of it, including the underground tubers.

Look for a glyphosate product with 41% to 54% active ingredient, and mix the product in water according to label directions. To do a 'spray-to-wet' application (in which the celandine leaves are sprayed until the surfaces are completely wet), mix the glyphosate product in water at 1% to 1.5% volume. Indicator dye should also be included in the spray mixture, so you can see where and how much you've applied. Most glyphosate products come with a surfactant included. If you buy one that does not have surfactant, you will need to purchase a surfactant that is intended for use with herbicides and include it in your spray mixture.

The treatment window is quite short, generally late-March through early-May in most of Pennsylvania. Ideally, treat the celandine before the end of April to minimize injury to native plants, which usually begin to emerge in late-April and May. Early-season applications in mid- to late-March (depending on location/temperature) may miss some plants that haven't fully emerged. Regardless of application timing, small celandine leaves can easily be hidden by leaf litter or other plant material on the ground, so you must be diligent in searching for your targets.

Note that glyphosate is a non-selective herbicide, meaning it will injure or kill most green plants that it contacts, so it's important to avoid spray contact with desirable plants as much as reasonably possible. However, some level of non-target damage is typically unavoidable and this reality should not deter you from treating the celandine. Desirable plants will grow back in time, or can be planted after the celandine is controlled. Allowing a lesser celandine infestation to go unchecked ultimately does much more ecological harm than killing some desirable plants along with the celandine.

If lesser celandine is invading a lawn, a triclopyr-ester product, such as Turflon Ester Ultra, can reduce the celandine without harming turfgrass. Ohio State Extension and Clemson University Extension also report that the active ingredients triclopyr, 2,4-D, dicamba, and MCPA can provide some control of lesser celandine when at least two of these ingredients are combined in the spray mixture. These are broadleaf-specific herbicides, meaning they will not harm grasses, and lawn-&-turf products are available that contain these ingredients. Another active ingredient mentioned in the research literature is metsulfuron-methyl, which is also available in lawn-care products.

However, it should be noted that glyphosate will generally provide the best control of lesser celandine, and it may be better to simply treat the celandine clumps or patches with this and re-seed any spots where the grass is killed.

Regardless of which herbicide(s) you choose, follow the instructions on the label(s). If the celandine is growing near water or in a wetland, be sure to use only aquatic-labeled herbicide products and avoid spraying the water directly. Apply herbicides when the air temperature is at least 40°F. For use in lawns, read the label for specific instructions on different types of turfgrass. Do not mow lesser celandine, as this can spread the plant and can also reduce absorption of herbicides.

Treatment and Timing

Keep in mind that control efforts will need to be repeated once per year for at least a few years, probably more, especially for larger infestations. Broadleaf-specific or metsulfuron-methyl herbicides will likely take longer than glyphosate to eradicate a lesser celandine population. Even after the celandine seems to be eradicated, you should continue to monitor the site and surrounding area for several years to ensure that new infestations don’t start up.

What Can I Do About it on Other Property?

If you positively identify celandine somewhere other than your own property, you can report it, which is very helpful to land managers. If you find celandine on public land, report it to the agency or organization that oversees the land. Additionally, whether you find the celandine on public or private land, you can report it through a website or smartphone app, such as EDDMaps, iMapInvasives, or iNaturalist. Take good photos of the celandine and upload them with your report so experts can confirm the identity of the plant. Reporting invasive plants through these platforms helps agencies and land managers have a better idea of the locations and extent of infestations, which helps them with their planning and management efforts and predicting where the plants may spread.

Additionally, you can help our native ecosystems by spreading the word! Kindly encourage your neighbors and other people you know to suppress celandine and other invasive plants on their properties, and to purchase native plants for landscaping.

References

Axtell, A.E., DiTomasso, A., and Post, A.R. 2010. Lesser Celandine (Ranunculus ficaria): A Threat to Woodland Habitats in the Northern United States and Southern Canada. WSSA – Invasive Plant Science and Management, 3:190–196.

Boggs, J. 2023. Lesser Celandine: An Aggressive Non-Native Spring Ephemeral. BYGL – Ohio State University.

Coyle, D. and Williamson, J. 2019. Fig Buttercup. Home & Garden Information Center, Clemson Cooperative Extension.

Frey, M.N. and Schmit, J.P. 2017. Early-Season Treatment of Fig Buttercup (Ranunculus ficaria). Invasive Plant Science and Management, 10(2), pp:191–200.