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lesser celandine (Ranunculus ficaria)
ODA rating: B
 
USDA Symbol: RAFI
Oregon lesser celandine distribution

Other common names
fig buttercup, bulbous buttercup, small crowfoot

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Images courtesy of Tom Forney, Oregon Dept. of Agriculture
 

If images are downloaded and used from the ODA web site please be sure to credit the photographer.

Description
Lesser celandine is an herbaceous, perennial plant in the buttercup family (Ranunculaceae). Plants have a basal rosette of dark green, shiny, stalked leaves that are kidney to heart-shaped. The flowers open in March and April, have eight glossy, butter-yellow petals, and are borne singly on delicate stalks that rise above the leaves. Pale-colored bulblets are produced along the stems of the above ground portions of the plant, but are not apparent until late in the flowering period. When in bloom, large infestations of lesser celandine appear as a green carpet with yellow dots, spreading across the forest floor. There are many varieties of lesser celandine including a double-flowered form with many crowded petals and dark green leaves mottled with silvery markings. The primary reproductive method is the formation of turions that are produced on the roots in large numbers. They survive for years and are easily moved in contaminated dirt or by water. Seeds may also play a role in plant dispersal. Lesser celandine prefers shaded to partially shaded sites though it can thrive in full sun with adequate soil moisture. Deciduous woods are an excellent habitat for this species enabling the plant to grow and bloom well before leaf initiation in the forest canopy.

Impacts
This species can impact forest environments by forming dense patches leading to the exclusion of many low-growing forbs especially early-blooming native wildflowers. To the private landowner or gardener, lesser celandine escaping from plantings quickly overwhelm flowerbeds and lawns. Contaminated garden loam applied to new lawns can create problems in a few short years. Because of the bulbous nature of the root system, control can be difficult. Bulb fragments are easily overlooked during manual control, leading to re-infestation. Chemical control must be timed for optimal kill but the nonselective nature of certain herbicides can lead to non-target impacts on desirable plants. The bloom period for this species runs early March through May starting well before leaf formation in deciduous forests. Monotypic stands are formed under forest canopies pushing out native understory plants. Cultivars of lesser celandine continue to be sold through catalogs and nurseries nationwide.
 
Introduction
Lesser celandine is frequently found in many northeast states where it has escaped from gardens and has invaded surrounding deciduous forests. The species is currently found in 19 states and reported invasive in nine. Some National Parks in the eastern U.S are host to lesser celandine outbreaks. Infestations in the western states are mostly limited to urban parks and private yards where plantings have grown out of control. Planted originally as an ornamental species, lesser celandine escaped cultivation and now has spread throughout the Northeast, Midwest and into the Pacific Northwest states.

Distribution in Oregon
Small populations can be located in the larger Willamette Valley communities of Portland, Salem and Eugene-Springfield. A five acre infestation in Wilsonville was converted into a city park. This was the largest known infestation in Oregon.

 
Biological controls
Biological control agents are not available for this plant at this time.
 
Printable trifold of lesser celandine (pdf)