Listed as invasive in 25 states. Rapidly spreads throughout low-lying wetland areas, displacing native plants, removing habitat for native animals, and disrupting hydrological flows.

Listed as invasive in 23 states. Spreads by birds dropping seeds and rapidly overtakes the forest floor, forming a dense understory and preventing forest regeneration. Harbors the ticks that carry Lyme disease.

Listed as invasive in 20 states. Spreads by birds dropping seeds and rapidly overtakes the forest floor, forming a dense understory and preventing forest regeneration.

Listed as invasive in 17 states. This new version of the newly banned “Bradford” pear is purported to be “sterile,” just like they claimed the Bradford pear was. Bradford pears regained their fertility and spread like wildfire, destroying farm fields and woodlands across the country.

Listed as invasive in 16 states. Spreads by birds dropping seeds and rapidly overtakes the forest floor, forming a dense understory and preventing forest regeneration.

Listed as invasive in 16 states. English ivy forms dense mats on the ground, crowding out all other native plants and preventing forest regeneration. It climbs trees and weights them down, making the trees susceptible to breakage during storms.

Listed as invasive in 15 states. Vigorously reproduces through massive seed production. Seeds are carried on the wind. Norway maple grows quickly and takes over the forest, crowding out native trees.

Listed as invasive in 14 states. Spreads into forests via birds dropping seeds. Wintercreeper climbs trees and smothers them, preventing photosynthesis and killing the tree.

Listed as invasive in 13 states. Also known as Japanese blood grass, Cogon grass is regarded as one of the worst invasive plant species worldwide. It spreads via rhizomes and is extremely difficult to eradicate.

Listed as invasive in 12 states. Reproduces through wind-dispersed seeds and rhizomes. This grass can form extensive infestations by escaping from established ornamental plantings into disturbed areas where it forms dense clumps that displace native vegetation. Highly flammable, it is notorious for being a fire hazard.

Listed as invasive in 12 states. Spreads by birds dropping seeds and rapidly overtakes the forest floor, forming a dense understory and preventing forest regeneration.

Listed as invasive in 12 states. Reproduces by seed, roots and plant fragments. Scotch broom displaces native vegetation and beneficial plants, causing loss of grassland and open forest habitat. The seeds and other plant parts are toxic to humans, horses, and other livestock. In the year 2000, the Oregon Department of Agriculture estimated the financial impact of Scotch broom infestations to Oregon at 47 million dollars.

Listed as invasive in 11 states. Rapidly spreading vine that forms a dense carpet across the forest floor and prevents tree and shrub seedlings from establishing. Crowds out native plants and provides no food sources for native animals.

Listed as invasive in 10 states. Also known as “Heavenly bamboo,” Nandina spreads rapidly as birds drop the seeds. The berries are toxic to Cedar waxwings and have led to the sharp decline of this beloved backyard bird.

Listed as invasive in 9 states. Spreads by birds dropping seeds and rapidly overtakes the forest floor, forming a dense understory and preventing forest regeneration.

Listed as invasive in 9 states. Also known as Creeping Jenny, Moneywort is a low-growing herbaceous invasive perennial that threatens wetland areas. It is still widely available in the nursery trade and is commonly sold as the cultivars ‘Aurea’, ‘Goldi’, or 'Goldilocks'.

Listed as invasive in 8 states. Japanese spirea has small seeds that wash away and rapidly take over disturbed areas; they are especially a problem when they reach stream banks. Seeds may also arrive in fill dirt used in home construction. Once established, Japanese spirea forms dense stands that outcompete the native forest flora. Seeds can last for years in the soil, making the spread difficult to control.

Listed as invasive in 7 states. Easily invades wetland areas, swamps, blackwater streams, and riverine forests; often colonizes lake banks and forms dense growth. It can tolerate a wide range of wet to dry sites. It will form dense stands along lakes and rivers where it completely eliminates native plant species. Infestations alter natural habitat and ecosystem processes, reducing biodiversity.

Listed as invasive in 6 states. Common along riverbanks and river gravel bars where it out-competes native plants and alters soil nutrients. Butterfly bushes form dense, shrubby thickets that exclude all other plants and displace native vegetation such as willows. They can supplant other plants as nectar sources and thus reduces their pollination. It likely negatively affects native butterfly populations. Once established, it is difficult to remove because it re-sprouts very easily.

Listed as invasive in 6 states. Plants spread by seed. Seeds are very light and can be dispersed in the wind and by human activity. Vegetative spread can occur when fragmented roots receive adequate moisture and develop adventitious roots. Pampas grass is a fire hazard and increases the risk to structures during wildfires.

Listed as invasive in 6 states. Sawtooth oak, a tree native to eastern Asia, is popular for use in street tree plantings due to its interesting foliage and fruits (acorns). It spreads by seed that is produced in large numbers and has been found in recent years to be escaping from plantings to become invasive in wild areas, displacing native plants.

Listed as invasive in 4 states. Reproduces by seed that is spread by wind, water, and animals. Fountain grass is a highly aggressive, fire- adapted colonizer that readily outcompetes native plants and rapidly reestablishes after burning. Fountain grass is a major threat to some critically imperiled plant species and natural communities. It raises fuel loads, which increases the intensity and spread of a fire, and results in severe damage to native, dry forest species adapted to less extreme fire regimes.

Listed as invasive in 4 states. Lantana camara is native to Central and South America and occurs in open to partly shaded moist areas. It was introduced into the United States in the 1800s and is still sold as an ornamental for landscaping. May be confused with threatened native species with which it readily hybridizes.

Listed as invasive in 3 states. Spreads through rhizomes. Expansion is most rapid on moist, highly organic soils. The most extensive infestations of Liriope are typically found at old abandoned home sites and in woods adjacent to neighborhoods. Solid infestations of Liriope displace native plants to form monocultures that can severely degrade natural habitats and contribute to population declines of native flora and fauna.

Listed as invasive in 2 states. Invades roadsides, in old fields and in other disturbed habitats. It can also invade natural areas such as floodplain forests and woodlands. It may displace shrubs in regenerating communities and remain persistent in these areas. Ligustrum ovalifolium can form dense thickets that outcompete many kinds of native vegetation.

Listed as invasive in 2 states. It is a moderately vigorous, deciduous climber or a scrambling shrub that typically forms a mass of stems and grows up to around 27 feet long. Chinese clematis forms dense infestations that outcompete native plants and can kill small trees.

Listed as invasive in 2 states. Reproduces from seed. It can also reproduce from pieces of the root crown. Common fennel escapes cultivation and quickly establishes dense infestations that crowd out native plants that are critical to wildlife habitats. May pose a threat to native grasslands.

Listed as invasive in 2 states. It is a hardy perennial that spreads to form dense mats of groundcover. Japanese pachysandra can quickly overrun the intended garden boundaries, escaping into the natural landscape and outcompeting native plants.

Listed as invasive in 2 states. Spreads by runners that spread above and just below the ground's surface. Peppermint has escaped cultivation and invaded forests, forming dense patches that crowd out native species and prevent native tree seedlings from establishing.

Listed as invasive in 1 state. Seeds can be spread by birds, waterways, and people. Shade tolerant, it can spread into native forests. Seeds may remain viable in the soil for two years. Dahoon holly is able to resprout after cutting and pruning. It was intentionally planted by territorial and state foresters along Highway 11 from ‛Ōla‛a to Volcano from 1940-1960. It may be slightly toxic.

Listed as invasive in 1 state. Highly invasive in some areas, it competes aggressively with native species and can therefore exclude and replace native vegetation. European blackberry forms dense, impenetrable thickets. Can spread by birds dropping seeds. The plant growth habit is a running thicket forming a colony from shoots away from the crown spreading indefinitely. The root pattern is suckering with new plants from underground runners away from the plant.

Listed as invasive in 1 state. Spreads prolifically both with seed and through tubers. Italian arum has orange-red berries that grow in oblong clusters and can be toxic to humans and wildlife, and its oils are a known skin irritant. Despite the fact that it is invasive, toxic, and its flowers emit an unpleasant aroma, it is still a commonly sold ornamental.

Listed as invasive in 1 state. It is often used as a landscape ornamental plant and produces prolific quantities of seeds which are carried by wind and stormwater. Japanese maple can be found in yards, along roadsides, and streams. Widespread use of this plant increases the probability that more will escape from cultivation.

Listed as invasive in 1 state. Prefers disturbed areas, including roadsides, coastal scrub, prairie and forests. Crocosmia is a superior competitor for water, light and nutrients, and it excludes native plants by growing in dense patches. It reproduces using seeds and underground corms. Upon introduction to a new area, crocosmia spreads slowly at first, then more rapidly as the species becomes established.