Invasive Plants

Common Buckthorn - Also known as European Buckthorn, Hart's Thorn, and European Waythorn, Common Buckthorn was brought to the U.S. in the mid-1880s as a hedging material and was quickly recognized as being aggressively invasive. Buckthorn out-competes native plants, degrades wildlife habitat, serves as a host to crown rust fungus and soybean aphid, and lacks any natural "controls" such as insects or diseases.

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Common Reed - Common Reeds can rapidly form dense stands of stems which crowd out or shade native vegetation in inland and estuary wetland areas. They turn rich habitats into monocultures devoid of the diversity needed to support a thriving ecosystem. Non-native reeds can alter habitats by changing marsh hydrology; decreasing salinity in brackish wetlands; changes local topography; increasing fire potential; and outcompeting plants, both above and below ground. These habitat changes threaten the wildlife that depend on those wetland areas for survival.

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Exotic Bush Honeysuckles - Native to Japan, China, Korea, Manchuria, Turkey and southern Russia, Bush Honeysuckles were first imported as a landscape plant. Relatively shade-intolerant, they most often occur in forest edge, abandoned field, pasture, roadsides and other open, upland habitats. Exotic bush honeysuckles can rapidly invade and overtake a site, forming a dense shrub layer that crowds and shades out native plant species.

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Garlic Mustard - Garlic mustard is an invasive herb that has spread throughout much of the United States over the past 150 years, becoming one of the worst invaders of forests in the American Northeast and Midwest. While it is usually found in the undergrowth of disturbed woodlots and forest edges, recent findings have shown that garlic mustard has the ability to establish and spread even in pristine areas. This spread has allowed it to become the dominant plant in the undergrowth of some forests, greatly reducing the diversity of all species. Garlic mustard is one of very few non-native plants to be able to successfully invade forest understories.

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Giant Hogweed - Giant hogweed is one of New York's most striking and dangerous invasive plants. A member of the carrot or parsley family, it was originally from Eurasia, but was introduced to the United States and Canada in the early 1900s as an ornamental, for use in beekeeping and for the use of its seeds as a spice. Since then it has spread outside of cultivation and established itself in areas around the country.

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Japanese Barberry - Japanese Barberry was introduced in 1875 and promoted as an ornamental substitute for common barberry (Berberis vulgaris), which is a host for black stem rust. Prevalent in the East and Midwest of the United States, it forms dense stands that compete with native trees and plants.

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Japanese Knotweed - Japanese knotweed, a member of the buckwheat family, was introduced into the U.S. from Eastern Asia in the late-1800s. By the late-1930s, it was viewed as a problematic pest. The plant, which can grow from three to 15 feet tall, has bamboo-like stems and is sometimes called Japanese bamboo. As with many invasive plants, knotweed thrives in disturbed areas and once established can spread rapidly, creating monoculture stands that threaten native plant communities.

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Japanese Stiltgrass - Japanese Stiltgrass was probably introduced to the U.S. as packing material in crates from China. It can grow in a variety of habitats where it forms dense stands and crowds out native species.

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Multiflora Rose - Native to eastern China, Japan and Korea, Multiflora Rose was introduced to the U.S. from Japan in 1866, as rootstock for grafted ornamental rose cultivars.It subsequently has been promoted as a means to prevent soil erosion, as wild habitat, and for highway median plantings. Currently, mulitflora rose is found in 41 states. It is classed among the top forest invasive plant species for the northeastern area by the US Forest Service.

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Oriental Bittersweet - Oriental Bittersweet was introduced in the 1860s as an ornamental and for erosion control. It grows as a vine that girdles and smothers plants and uproots trees due to its weight.

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Swallow-Worts - Three species of swallow-wort are currently found in North America, two of which are considered invasive: black swallow-wort and pale swallow-wort. It is a member of the plant family Asclepiadaceae, like milkweed. It is native to Europe but started spreading in the United States when it began escaping from Massachusetts botanical gardens in 1864.

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Tree of Heaven - Tree of Heaven was introduced in the late 1700s. It crowds out native species; damages pavement and building foundations in urban areas.

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Wild Parsnip - Wild parsnip is an invasive plant from Europe and Asia that has become naturalized in North America. It has been around for years but only recently is it really becoming widespread. It is well suited for colonizing disturbed areas but can also be found in open fields and lawns. Wild parsnip sap can cause painful, localized burning and blistering of the skin that can cause blisters and skin discoloration. The scarring cause from the skin irritation can last for years.

If you have any questions about invasive species locally or if you think you have an invasive species to identify or report, please contact David Gray Cox at dgc23@cornell.edu or (518) 234-4303 or 296-8310.

Last updated July 16, 2020