Skip to main content
U.S. Forest Service
Caring for the land and serving people

United States Department of Agriculture

Invasive Forest Plants

Preventing or reducing undesirable impacts of non-native invasive plants is a difficult challenge facing all land managers. Non-native invasive plants impact landscapes across the U.S. through changes in the structure, composition, and successional pathways of native plant communities.

Forest Health Protection provides funding, technical assistance, and technology development to support invasive plant species programs on non-Federal lands and, in tropical forests, on Federal lands, excluding National Forest System lands. Forest Health Protection specialists work closely with weed management cooperators, States, Tribes, U.S. Territories, and Freely Associated States to manage invasive plant program activities. Technical assistance includes providing entomology and pathology expertise in the implementation of biological control program efforts.

Forest Health Protection also provides assistance in pesticide use, including herbicide risk assessments, which are requirements for the environmental analysis of NFS invasive plant control programs. Visit Pesticide Management & Coordination for more information.

Invasive Forest Plant Range Maps

The invasive plant distribution maps were derived from data collected through an integration of various sources (e.g., EDDMapS, the USDA Forest Service, and State-collected data) and were reviewed by regional authorities. They are intended to display the range over which these invasive plants have been detected or established.

Invasive Forest Plant Range Maps
Invasive Plant Common Name Invasive Plant Scientific Name
Buffelgrass Cenchrus ciliaris
Canada thistle Cirsium arvense
Cogongrass Imperata cylindrica
Japanese honeysuckle Lonicera japonica
Mile-a-minute vine Persicaria perfoliata
Purple loosestrife Lythrum salicaria
Saltcedar Tamarix ramosissima
Spotted knapweed Centaurea stoebe ssp. micranthos
Tree-of-heaven Ailanthus altissima
Yellow toadflax Linaria vulgaris
Invasive plants

Removing mud and seeds from your shoes can help prevent the spread of invasive plants and animals. (Photo by Kim Lanahan-Lahti, Minnesota Department of Natural Resources, Division of Forestry). A New Way to Stop Invasive Pests – Clean Recreation. Read more

Invasive Forest Plant Range Map

Invasive Forest Plant Range Map


Garlic mustard

Photo by David Cappaert,

Garlic Mustard

Garlic mustard, an aggressive plant invader of wooded areas throughout the Northeastern and Midwestern United States, can form dense stands and displace native species by competing for available light, nutrients and water resources.
Learn more

Giant hogweed

Photo by Thomas B. Denholm, New Jersey Department of Agriculture,

Giant Hogweed

Giant hogweed is a tall, herbaceous, biennial plant that invades disturbed areas across both the Northeastern and Pacific Northwestern US. It is designated as a Federal Noxious Weed.

Learn more

Medusa head

Photo by Steve Dewey, Utah State University,

Medusa Head

Medusahead is an annual grass native to the Mediterranean region of Europe. It establishes and dominates on sites where the native vegetation has been eliminated or severely reduced by overgrazing, cultivation, or frequent fires.

Learn more


Photo by James H. Miller, USDA Forest Service,


The Albizia tree is a challenging invasive species for the Island of Hawaii. It spreads rapidly, forms a broad canopy, and is fast growing, reaching 30 feet in three years. Mature trees can exceed 100 feet and cover a wide area.

Learn more


Photo by Tom Heutte, USDA Forest Service,


Knotweeds are all large, robust perennials in the Buckwheat family introduced from Asia to North America. Knotweed clones can completely clog small waterways and displace streamside vegetation, increasing bank erosion and lowering the quality of riparian habitat for fish and wildlife.
Learn more


Photo by John M. Randall, The Nature Conservancy,


Cheatgrass has developed into a severe weed in several agricultural systems throughout North America, particularly western pastureland, rangeland, and winter wheat fields. It is now estimated to infest more than 101 million acres in western states.
Learn more