Invasive species is defined as any non-native animal, plant or microbe introduced into the ecosystem that causes or can cause harm to the environment, economy or human health.
Top plant invasive's are ......Japanese Honeysuckle (Lonicera japonica)
......................................... Japanese Barberry (Berberis thunbergii)
......................................... English Ivy (Hedera helix)
......................................... Kudzu (Pueraria montana var. lobata)
......................................... Japanese Knotweed (Fallopia japonica)
JAPANESE HONEYSUCKLE
https://en.wikipedia.org/wiki/Lonicera_japonica
Came to Long Island NY for ornamental use and erosion control in 1806. Spread to most of the east coast where its climbing ability smothers, shades and girdles native vegetation.
JAPANESE BARBERRY
Also came to the US for ornamental reasons in the 1800's. Can withstand deep shade while forming dense thickets crowding out native plants. Spiny branches act like thorns making them impenetrable.
ENGLISH IVY
Brought to US in early 1700's as a ground cover. An aggressive-spreading vine which can slowly kill trees. Can grow in wide spreading conditions mostly on the east and west coasts.
KUDZU
Introduced by Japan at the Philadelphia Centennial Exposition in 1876. Presented as an ornamental plant and later as a forage crop in the Southern US region. One million acres of Kudzu were planted in the 1930s and 1940s for soil conservation. Boy did that backfire.
The vine can grow a foot a day and 60 feet {18 meters] in a year. The use of herbicide spraying and mowing costs millions of dollars each year and the vine continues to spread.
JAPANESE KNOTWEED
Listed by the World Conservation Union as one of the world's worst invasive species.Arrived in the USA in the late 1800's as an ornamental. Very hard to eradicate as roots can travel 10 feet deep. Can damage concrete foundations, roads and can crowd out all other species.
These are some of the worst, I'm sure you can think of others and there will definitely be more in the future.
sources
wikipedia
https://insider.si.edu/2013/04/top-six-invasive-plant-species-in-the-united-states/