Ranunculus ficaria is a perennial plant and spring ephemeral (lasting for a very short time) that spends much of the year underground as thickened tubers. In the North American region, native ephemeral wildflowers grow and flower early in the spring before leaf-out of the forest canopy. Ranunculus ficaria uses this same strategy, but starts growing earlier in the season and is far more aggressive in its use of space. It out-competes native plants through its extremely early seasonal growth and forms extensive carpets in natural areas, crowding out native plants. Management primarily consists of delicate chemical treatments that must occur before native species emerge. Care must also be taken not to cause harm to flora that is emergent during chemical treatments.
R. ficaria commonly known as lesser celandine is a low-growing perennial herb with shiny, somewhat lustrous dark green leaves that form a rosette. Leaves are kidney to heart shaped with smooth to coarse toothed edges. Each rosette forms a single bright yellow flower that is up to 2.5cms (one inch) wide. Seeds ripen early and the entire plant dies back by early summer, but not before it has developed numerous tubers in which it has stored energy for early growth the next year. Large colonies of R. ficaria can cover acres of forest floor. They are easy to spot in the spring because of the high density of bright yellow flowers on the bright green carpet of leaves. R. ficaria measures 10-30cm long. The leaves measure 1.8-3.7cm long and 2-4cm wide. The flowers of R. ficaria measure 1-2cm across. The head of the achene is globose in shape and measure about 1.25cm across.”
Natural forests, planted forests.
R. ficaria occurs in moist forested floodplains and in some drier upland areas, and seems to prefer sandy soils.”
R. ficaria is primarily a threat to native plants and native plant diversity in lowland woods and on flood plains. It out competes native plants through its extremely early seasonal growth and the development of a dense network of roots and tubers in the soil. Over time it forms extensive carpets in natural areas, crowding out native plants, especially native ephemeral (short-lived) wildflowers. The survival strategy of native ephemeral wildflowers is to grow and flower early in the spring before leaf-out of the forest canopy. By doing so, these plants receive needed sunlight and can take advantage of nutrients released from decaying material over the winter. R. ficaria uses the same strategy, but starts growing earlier in the season and is far more aggressive in its use of space. Unfortunately, R. ficaria is still available commercially for garden plantings.
Native range:Africa, Asia, Europe
Known introduced range: North America
Chemical: R. ficaria is very difficult to control but it can be managed with persistence over time using methods that are site appropriate. While manual methods are possible for some small infestations, the use of systemic herbicide kills the entire plant tip to root and minimizes soil disturbance. The window of opportunity for controlling R. ficaria is very short, due to its life cycle. In order to have the greatest negative impact to R. ficaria and the least impact to desirable native wildflower species, herbicide should be applied in late winter-early spring. Apply glyphosate isopropylamine salt mixed with water and a non-ionic surfactant to foliage, avoiding application to anything but the R. ficaria. To minimize impacts to sensitive-skinned frogs and salamanders, some experts recommend applying herbicide in March and then switching to manual methods.
For small infestations, R. ficaria may be pulled up by hand or dug up using a hand trowel or shovel. It is very important to remove all bulblets and tubers.” The authors caution that mechanical control is considered inappropriate for large infestations in high quality natural areas because of disturbance to soil.