NATIVE
RANGE
Europe
DESCRIPTION
Lesser celandine, also known
as fig buttercup, is an herbaceous, perennial plant. 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.
NOTE: Lesser celandine
closely resembles marsh marigold (Caltha palustris), a native wetland
plant that occurs in the eastern United States. Marsh marigold is a robust
plant with glossy, rounded or kidney-shaped leaves and flowers on stalks
that are 8 in (20.3 cm) or more in height and consist of five to nine deep
yellow "petals" (actually sepals). Marsh marigold does not produce tubers
or bulblets, nor does it form a continuous carpet of growth. Extreme care
should be taken to correctly identify lesser celandine before undertaking
any control measures to avoid impacts to this plant.
ECOLOGICAL THREAT
Lesser celandine is
an exotic spring ephemeral and a vigorous growing groundcover that forms
large, dense patches on the forest floor, displacing and preventing native
plants from co-occurring. The ecological impact of lesser celandine is primarily
on the native spring-flowering plant community and the various wildlife species
associated with them. Spring ephemerals complete the reproductive part of
their life cycle and most of their above-ground development before woody
plants leaf out and shade the forest floor. Native spring ephemerals include
bloodroot, common and cut-leaved toothwort, Dutchman's breeches, harbinger-of-spring,
squirrel-corn, trout lily, Virginia bluebells, and many others. Because lesser
celandine emerges well in advance of the native species, it can establish
and overtake areas rapidly.
DISTRIBUTION
IN THE UNITED STATES
Lesser celandine is currently found in nineteen
states in the Northeast and Pacific Northwest (USDA
PLANTS map). It is reported to be invasive in nine states (Connecticut,
Delaware, Maryland, New Jersey, Oregon, Pennsylvania, Virginia, Wisconsin,
West Virginia), and the District of Columbia (WeedUS
Database).
HABITAT IN THE UNITED STATES
Lesser
celandine occurs in moist forested floodplains and in some drier upland areas,
and seems to prefer sandy soils.
BACKGROUND
Lesser celandine was introduced
to the United States as an ornamental plant. It is still available commercially
in the U.S., along with many colorful varieties. All varieties of lesser
celandine should be assumed to be invasive.
BIOLOGY & SPREAD
Lesser celandine
is an exotic perennial plant and spring ephemeral that spends much of the
year (summer through early winter) underground as thickened, fingerlike tubers
or underground stems. During the winter, leaves begin to emerge and photosynthesize
in preparation for flowering. Flowering usually occurs from late winter through
mid-spring (March through May), depending on conditions. Afterwards, the
above-ground portions die back. Lesser celandine spreads primarily by vegetative
means through abundant tubers and bulblets, each of which is ready to become
a new plant once separated from the parent plant. The tubers of lesser celandine
are prolific and may be unearthed and scattered by the digging activities
of some animals, including well-meaning weed pullers, and transported during
flood events.
MANAGEMENT OPTIONS
Lesser celandine
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.
Biological
No biological control agents
are currently available for lesser celandine.
Chemical
The window of opportunity for
controlling lesser celandine is very short, due to its life cycle. In order
to have the greatest negative impact to celandine and the least impact to
desirable native wildflower species, herbicide should be applied in late
winter-early spring (March through May). Apply a 1.5% rate of a 39 to 41%
glyphosate isopropylamine salt (e.g., Rodeo® for wetland areas) mixed with
water and a non-ionic surfactant to foliage, avoiding application to anything
but the celandine. Glyphosate is systemic; that is, the active ingredient
is absorbed by the plant and translocated to the roots, eventually killing
the entire plant. The full effect on the plant may take 1-2 weeks. Applications
can be made during the winter season as long as the temperature is above
about 50 degrees Fahrenheit, and no rain is anticipated within 12 hours.
Because glyphosate is non-specific, spray should be controlled such that
it touches only lesser celandine and does not drift onto desirable plants.
To minimize impacts to sensitive-skinned frogs and salamanders, some experts
recommend applying herbicide in March and then switching to manual methods.
Manual
For small infestations, lesser
celandine 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.
Mechanical
If mechanical removal is
to continue after dieback of the plants, individual plants or clumps will
need to be marked with some sort of stakes or flagging because it will be
impossible to relocate the plants otherwise. When conducting mechanical removal,
care should be taken to minimize soil disturbance as much as possible. For
this reason, mechanical control may be inappropriate for large infestations
in high quality natural areas.
USE PESTICIDES WISELY: ALWAYS READ THE ENTIRE PESTICIDE LABEL CAREFULLY, FOLLOW ALL MIXING AND APPLICATION INSTRUCTIONS AND WEAR ALL RECOMMENDED PERSONAL PROTECTIVE GEAR AND CLOTHING. CONTACT YOUR STATE DEPARTMENT OF AGRICULTURE FOR ANY ADDITIONAL PESTICIDE USE REQUIREMENTS, RESTRICTIONS OR RECOMMENDATIONS.
NOTICE: MENTION OF PESTICIDE PRODUCTS ON THIS WEB SITE DOES NOT CONSTITUTE ENDORSEMENT OF ANY MATERIAL.
CONTACTS
For more information on
the management of lesser celandine, please contact:
- Sue Salmons, Natural Resources Manager,
National Park Service, Rock Creek Park, Washington, DC, sue_salmons at nps.gov
- Jil Swearingen, Integrated Pest Management
Coordinator, National Capital Region, Center for Urban Ecology, Washington,
DC, jil_swearingen at nps.gov
SUGGESTED ALTERNATIVE PLANTS
Many lovely,
perennial, spring-flowering plants are available as non-invasive alternatives
to lesser celandine. Some examples of plants native the eastern U.S. include
wild ginger (Asarum canadense), Dutchman's breeches (Dicentra cucullaria),
squirrel-corn (Dicentra canadensis), cutleaf toothwort (Cardamine concatenata),
twinleaf
(Jeffersonia diphylla), and bloodroot (Sanguinaria canadensis).
Contact your local native plant society for additional suggestions and assistance.
The Plant Conservation Alliance provides links to many groups at (http://www.nps.gov/plants).
OTHER LINKS
AUTHOR
Jil M. Swearingen, National Park Service,
National Capital Region, Center for Urban Ecology, Washington, DC
REVIEWERS
Carole Bergmann, Sally Gagne, Larry Morse,
Ann Rhoads, Steve Young
PHOTOGRAPHS
Jim Stasz @ USDA-NRCS PLANTS Database
Olivia Kwong, Plant Conservation Alliance, Washington, DC
REFERENCES
Bailey, L.H. and E.Z.
Bailey. 1977. Hortus Third: A Concise Dictionary of Plants Cultivated in the
United States and Canada, MacMillan Publishing Co., Inc., New York.
Fernald, M. L. 1970. Gray's Manual
of Botany, Eighth edition. D. Van Nostrand Company, New York, NY. p. 648.
Peterson, R.T. and M. McKenny. 1968.
A field guide to wildflowers Northeastern and North-central America: Houghton-Mifflin
Co., Boston, MA. 420 pp.
Salmons, S. 2003. Presentation to
Mid-Atlantic Exotic Pest Plant Council, University of Pennsylvania, Philadelphia,
PA.
Strasbaugh, P. D. and E. L. Core.
Flora of West Virginia, Second Edition. Seneca Books, Inc. Grantsville, WV.
Swearingen, J. 2004. WeedUS: Database
of Invasive Plants of Natural Areas in the U.S. (in progress). http://www.nps.gov/plants/alien.
Plant Conservation
Alliance, Alien Plant Working Group.
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