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Japanese stiltgrass, Nepalese browntop
NATIVE RANGE:
Europe
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. For more information
on lesser celandine, please contact: Jil Swearingen, Integrated Pest Management
Coordinator, National Capital Region, Center for Urban Ecology, Washington, DC
(jil_swearingen@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). 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. 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. Plant Conservation Alliance, Alien Plant Working Group. |
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