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Invasive species to look out for and report

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    Wild chervil

    Help prevent new invasive species from getting introduced to Wisconsin and gaining a foothold. Report when you see infestations of the following species on Wisconsin’s prohibited list. Report your sightings to invasive.species@Wisconsin.gov, providing a photo, location and contact information.

    Wild Chervil, also known as cow parsley or bur chervil, blooms in early June. It is spread by roadside mowing and then invades open woods, fields and pastures, where it out-competes native and desirable plants. It is native to Europe and has been planted as an ornamental.

    Learn how to identify this invasive plant and see more photos.
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    Amur cork trees

    Amur cork trees have been present in Wisconsin for a while – they were planted as landscaping -- but are starting to spread as birds carry their seeds and disperse them. The trees outcompete other plants in forests.

    Learn how to identify this invasive tree and see more photos.
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    Lesser celandine

    Lesser celandine is a groundcover with kidney to heart-shaped leaves and showy, buttercup yellow flowers that invades forests, wetlands and shoreland areas, as well as upland areas and disturbed areas such as lawns. The invasive is poisonous to livestock and humans, and infestations of this plant eliminate spring wildflowers in woodlands.

    Learn how to identify this invasive plant and see more photos.
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    Porcelain berry

    Porcelain berry (Ampelopsis brevipedunculata) is an ornamental plant from east Asia that spreads aggressively, climbing trees and shrubs, eventually blanketing the forest. The vine has been found on hundreds of properties on the west side of Madison so far.

    Learn how to identify this invasive plant and see more photos.
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    Southern pine beetle

    This tiny bark beetle is native to the southern U.S., Mexico and Central America. It has expanded into New England, perhaps due to warming temperatures. The beetles are attracted to weakened mature pine trees.
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    Beech leaf disease

    This disease is a serious issue in parts of Ohio, West Virginia, Pennsylvania, New York and Ontario. Its suspected cause is an invasive nematode. Affected trees are vulnerable to attack by myriad insects and pathogens.

    Learn how to identify this invasive plant and see more photos.
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    Asian longhorned beetle

    This beetle is a threat to Wisconsin's hardwood trees. It currently infests parts of Massachusetts, New York and Ohio, where it threatens recreation and high-value forest resources.

    Learn more about this invasive insect and see more photos.
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    Giant hogweed

    Giant hogweed, which can severely burn people who touch it, has been found in Iron, Portage, Manitowoc and Sheboygan counties and is being aggressively managed to stop its further spread. It grows along roadsides, empty lots and woodland edges and its rapid growth rate allows it to outcompete native plants. It is distinguished from American cow parsnip by its size – it can grow up to 15 feet tall with giant leaves up to 5 inches wide -- and green stalks with dark purple splotches and coarse white hairs.

    If you need help identifying this plant, please send a clear photo of the leaves and stalks, including something for scale, and your name and location of the plant to invasive.species@wisconsin.gov.
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    Carolina fanwort

    Taking root in freshwater, this plant has been a nuisance in New York, Michigan, and Oregon. It spreads on recreational equipment and through the aquarium trade. Its dense mats, harm other species, clog streams and canals, and impede recreation and agricultural water use.

    Learn how to identify this invasive plant and see more photos.Photo credit: Leslie Mehrhoff
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    European frog-bit

    This troublesome plant is present in Washington, New York, Vermont, and Michigan. Thick mats impede movement of boats and wildlife. Mats block light from submerged vegetation, and when they die, decreased oxygen kills other species.

    Learn how to identify this invasive plant and see more photos.Photo credit: Christian Fisher
Last Revised: Tuesday November 6, 2018