Top Ten Worst Invasive Plant Species

Kudzu

• Kudzu (Pueraria montana), a climbing vine, was introduced originally to the United States in 1876. Once promoted by the USDA for erosion control, it now is listed on several state's invasive species lists. It is a prolific grower with vines capable of growing up to 100 feet in length, spreading primarily by runners. Due to its dense growth habit, it kills other plants by blocking all sunlight.

Tree-of-Heaven

• The Chinese native tree-of-heaven (Ailanthus altissima) is a fast growing tree displacing native stands of trees. It was introduced first in the 1780s, and is found across the Unites States in urban and agricultural areas. It spreads through seed and vegetatively, and was planted also as an ornamental tree before it was recognized as an invasive plant.

Purple Loosestrife

• Purple Loosestrife (Lythrum salicaria) is native to Europe, and was introduced to the United States for ornamental and medicinal purposes in the early 1800s. It is found in wetland communities and spreads via prolific seeding. It forms dense stands that crowd out native herbaceous vegetation, which eventually can compromise wetland structure.

Phragmites

• Phragmites or common reed (Phragmites australis) is an invasive perennial grass found in wetlands and roadsides. Phragmites spreads vegetatively via rhizome and also by seed creating monocultures of dense vegetation. Crowding out native species, phragmites are found in marshy areas, along roadsides and in disturbed wet areas.

Cogon Grass

• Like many other invasives, cogon grass (Imperata cylindrica) forms dense stands that crowd out native species of plants and animals. It is found in the south and southeastern United States, and was introduced and touted for erosion control benefits.

Water Chestnut

• Water chestnuts (Trapa natans) are found in freshwater bodies primarily in the eastern United States although it has been observed in select western states. This aquatic invader was introduced in the mid 1800s for ornamental value. Forming floating dense mats on the surface of rivers, ponds and lakes, this invasive plant blocks light to other aquatic species, depletes oxygen levels, and crowds out other beneficial food plants for wildlife.

Cheatgrass

• Cheatgrass (Bromus tectorum) is another invasive perennial grass that thrives in disturbed areas primarily in the western United States. Its low nutrient needs and quick maturity give it a competitive advantage to the natives it displaces. Its biomass creates a fire hazard and alters the fire cycles in fire prone ecosystems. This Eurasian native was introduced in the mid 1800s and spreads primarily through seeds.

Japanese Knotweed

• Japanese knotweed (Fallopia jacponica) is an Asian native that was introduced in the late 1800s to the United States. This persistent herbaceous perennial spreads primarily via vegetative rhizomes and, once established, is difficult to eradicate. It is found in moist areas, often along riverbanks and riparian zones from the east to the west coast of the US.

Saltcedar

• Saltcedar (Tamarix ramosissima) is an invasive shrub found in the western United States. Displacing native plants, it alters food webs, increases fire hazard and increases soil salinity. It originally was introduced in the early 1800s for its ornamental value and still is found at garden centers for purchase by the home gardener.

Leafy Spurge

• Leafy spurge (Euphorbia esula) is an example of an herbaceous perennial introduced accidentally through seed contamination. This Eurasian native was brought over during the early 1800s and is widespread in fields and prairies, particularly in the northern and western states. Spread vegetatively and by exploding seed capsules, they crowd out native plants by densely populating disturbed and non-disturbed fields, roadsides and edge habitats.