Invasive Tree Types Guide: What Tree Species Are Invasive In US (Chart)

Some of the most beautiful types of trees are actually non-native and can be harmful to local ecosystems, making it very important for everyone to be aware of invasive tree types.

In fact, you’ll want to be very careful before planting any of these species.

Invasive trees often share some common characteristics, such as the production of large amounts of seed and swift disbursement, since there is a lack of natural controls (for example, animals that eat the fruit and seeds).

This article explores the most problematic invasive tree types in different regions of the United States and the United Kingdom and discusses management techniques for these species.

What Does the Term Invasive Mean?

The term “invasive,” as it applies to plants, indicates a foreign or non-native organism with a tendency to spread rapidly, causing undesirable or harmful effects to the local ecosystem.⁷⁴ “Exotic” is another word for non-native, and “invasive” is typically used to denote those exotic species that most aggressively out-compete native flora and attract non-native fauna which harm native plants.

According to the USDA National Invasive Species Information Center, any living organism can be deemed invasive if it demonstrates the defining qualities: non-native and potential for causing harm (economic, environmental, health).

The term “invasive” is not synonymous with “non-native,” as many established food crops and ornamental plants in the United States are exotic but do not cross the threshold for significant harm to ecosystems, human health, or the economy.⁶⁹

Note that “non-native” is defined in terms of the area under study, and by some definitions, it may not indicate origin in another country.

For example, it is possible for a species that is native in one area of the U.S. to be considered invasive in another area (See Robinia pseudoacacia, the black locust tree).

What Invasive Tree Types Are on the Invasive Species List in the United States?

According to the U.S. Register of Introduced and Invasive Species, more than 15,000 non-native plant and animal species have been introduced to the United States, and 25% of these species are considered invasive.⁵⁹

Independent researchers have reported 755 invasive plant species in the continental U.S.¹⁶

There are many many different resources on invasive tree types in the United States, and some invasive species lists are grouped by regions, states, or species type (See “Invasive Species Lists for the United States”).^65,71

The following table catalogs the exotic tree species which were listed on the Federal Noxious Weed List in 2010 for their invasive threat as well as some of the established offenders on the USDA Invasive Species Profiles List.

Certain species listed below are not on either of these lists but are problematic for various reasons which are explained further down.

*Information on invasive trees compiled from multiple sources.^{27, 28, 29, 40}

1. Black Locust

Robinia pseudoacacia is an interesting addition to the invasive tree list because it is actually native to the United States. Because it is fast-growing and produces excellent timber, the black locust tree has high economic value, and this is why it was planted on such a large scale across Europe.

Unsurprisingly, given its prolific seeding and root suckering habits which can lead to clonal groups, the false acacia has become invasive in many of the countries where it was introduced, such as Austria, Germany, Switzerland, and more.^44,75

What is surprising about this tree species is that it has become invasive in its native country as well.

The black locust is native to the Eastern United States, particularly common in the Appalachian and Ozark Mountain ranges, but it has spread and become established in other parts of the U.S., particularly the Midwest, where it out-competes local flora.⁷

2. Callery Pear

Pyrus calleryana, also known as the Callery pear, is an Asian native fruiting tree with ornamental value and well-known cultivars: the Bradford and Chanticleer Pear. Callery pear has become widespread across the United States since it was introduced a century ago.

The Callery pear is one of the first trees to flower in springtime, boasting dense inflorescences of small white flowers.

Because of its aesthetic value, it was regularly planted along streets and sidewalks. The Callery pear, however, proved difficult to contain.

A quick grower and prolific bearer of fruit, Pyrus calleryana is all but impossible to eliminate, as it attracts many types of birds which aid in widespread fruit dispersal. This tree and its cultivars should be avoided.¹⁸

3. Mesquite

There are approximately 45 species of mesquite (Prosopis spp.) in the Fabaceae family, all of which have demonstrated remarkably invasive tendencies. Most species of mesquite are native to South America, though some originate in Africa, Asia, and North America.

Two species are particularly problematic in the American South and Southwest: honey mesquite (Prosopis glandulosa) and velvet mesquite (Prosopis velutina).⁵¹

4. Prickly Acacia

Acacia nilotica, the prickly acacia, is a native of Africa and India and the surrounding areas. It has become established in many territories, including Australia, the Caribbean, and South America.

The prickly acacia is not currently widespread in the U.S., though it is listed as invasive in southern Florida. This tree is listed on the Federal Noxious Weed List, prohibiting anyone from bringing the plant into the country because of its demonstrated invasive potential.

The prickly acacia is established in U.S. territories: Puerto Rico and the U.S, Virgin Islands.⁴⁵

5. Princess Tree

Paulownia tomentosa, known as the princess tree or empress tree, was introduced from China in the mid-1800s because of its ornamental value. It is a mid-size tree that is extremely fast-growing, giving it an advantage over surrounding vegetation in the competition for sunlight and other resources.

It produces abundant woody capsules which can each contain up to 2,000 seeds. The spreading of these winged seeds on the wind makes it very difficult to control this invasive species.⁵⁵

6. Tree-of-Heaven

Ailanthus altissima has been in the United States since the late 1700s, when it was first introduced from its native China. It is now considered invasive throughout the contiguous U.S. and Hawaii, where it grows alongside other invasive tree types such as black locust, Norway maple, and princess tree as well as native oaks and hickories.²⁵

Tree-of-Heaven grows quickly, producing dense shade which impacts surrounding plant life. It is also believed to be allelopathic, harming nearby plants chemically.

Finally, Ailanthus altissima is particularly problematic due to its capacity for vegetative reproduction, producing abundant shoots from its roots and root crown to form dense stands.²⁵

7. White Poplar

Populus alba, the white poplar, is a native of Europe, Northern Africa, and temperate Asia. Since its North American introduction in the late 1700s, white poplar has become a common sight in the United States and Canada, particularly in the East.

Closely related to aspens, white poplar readily hybridizes with the European aspen, quaking aspen, bigtooth aspen, and Chinese aspen, increasing its invasiveness. Like its aspen relatives, white poplar spreads primarily through clonal growth.⁵⁷

Invasive Trees by Region of the U.S.

Some invasive trees are more problematic in certain areas of the U.S. due to their preferred climate and limits of competition (See “Invasive Species Lists by Region”). The following tables and lists expound on the invasive tree types that individuals living in various regions should be most aware of.

*Information on invasive trees compiled from multiple sources.^{32, 37, 53}

8. Amur Maple

Acer ginnala, the Amur maple, is invasive in both the Midwest and Northeast United States. It was introduced from Eastern Asia in the mid-1800s.

It is a small tree or shrub, growing only to 20 feet. It is known to be allelopathic, using chemicals to disadvantage nearby vegetation.

It is known to seed prolifically and outcompete native flora.³

9. Autumn Olive

The autumn olive, Elaeagnus umbellate, is another large shrub/small tree native to Asia which has become invasive in the Midwest and Northeast U.S.

It is an aggressive tree, with a wide area of seed dispersal and a high success rate of resprouting from stumps and roots. It is a difficult plant to eliminate.³⁸

10. Common Buckthorn

Rhamnus cathartica is a small tree which grows to about 25 feet in height. It is a Eurasia native which has established populations in the East and Midwest United States.

The common buckthorn spreads to form dense stands of growth which alter native ecosystems and displace natives.⁷²

11. European Birch

Betula pendula, the European birch, is believed to have escaped cultivation in the U.S. in the early 1900s.⁵ It has been reported as invasive in a handful of Midwestern states and is not recommended for planting due to its susceptibility to the bronze birch borer (Agrilus anxius).

12. European Black Alder

The European black alder, Alnus glutinosa, is restricted in some Midwestern states due to its invasive tendencies. Like many invasive tree types, it produces abundant amounts of seeds, hybridizes readily in the wild, and is highly successful in a variety of soil types.^6,22

*Information on invasive trees compiled from multiple sources.^29,52

13. Amur Cork Tree

The Amur cork tree (Phellodendron amurense) is an East Asia native introduced to the U.S. in 1850. It is a mid-size tree with compound leaves and bright yellow inner bark.

The Amur cork tree develops dense stands of growth which shade out surrounding vegetation, and it is also allelopathic, releasing chemicals which inhibit the growth of nearby plants.⁶⁸

14. Common Spindle Tree

Euonymus europaeus, the common spindle tree is a European native. It is shrublike in form but can grow to 30 feet in height.²⁰ It is a fast grower, adaptable, and tolerant of various soils.

It bears curious but attractive fruits which attract wildlife, in turn ensuring its own reproduction.²¹

15. Glossy Buckthorn

Rhamnus frangula is considered a shrub by many people because it has multiple stems until it reaches maturity and develops a trunk. It was introduced in the 1700s to be planted in hedgerows and privacy borders.

While most invasive trees spread by invading disturbed areas, the glossy buckthorn thrives equally in areas where the soil has not been disturbed.¹²

16. Japanese Angelica Tree

The Japanese angelica tree is a very fast-growing, aggressive tree. It is a small tree with fern-like leaves.

Aralia elata is problematic because it spreads rapidly by sprouting new stems from its roots and via birds which consume its seed.⁴

17. Norway Maple

The Norway maple (Acer platanoides) is one of several non-native maple trees that were introduced for their ornamental value. Unfortunately, it now outcompetes native maple trees in many areas of the United States.⁷⁷

It is fast growing and produces a dense canopy that shades out surrounding plant life.⁴³

18. Sycamore Maple

The sycamore maple (Acer pseudoplatanus) is tolerant of a wide range of soil types, and even thrives in high salinity. Like other maples, it produces abundant winged seeds which are easily dispersed by the wind.⁶⁰

*Information on invasive trees compiled from multiple sources.^29,61

19. Russian Olive

The Russian olive, Elaeagnus angustifolia, is one of the few noted invasive trees in the Western U.S. A native of Eurasia, it has been in the U.S. for over a century.⁷⁶

Russian olives are difficult to control because their roots are very deep and can resprout when the tree is cut back.³⁹

20. Saltcedar

The saltcedar, Tamarix ramosissima, often grows as a shrub though it can also grow to take the form of a small tree. It is problematic for several reasons.

It secretes large amounts of salt into the soil which hurt native plants and increases the spread of fires by providing abundant tinder. It greatly impacts riparian habitats.⁴⁶

21. Siberian Elm

Ulmus pumila is variably called the Siberian elm, the dwarf elm, the Chinese elm, or the Asiatic elm. It is a fast-growing, mid- to large tree which has become invasive in dry areas and can be particularly problematic in the Southwest.^24,78

Invasive Tree Types: What Types of Palm Trees in California Are Invasive?

Most of the palm trees growing in the state of California are non-native, having been introduced to the state from other areas of the country and even other countries entirely. Only one palm species, the California Palm (Washingtonia filifera), is native to the state.

Other types of palm trees in California are even considered invasive,⁵⁶ such as the Mexican Fan Palm (Washingtonia robusta).³³

*Information on invasive trees compiled from multiple sources.^{34, 35, 47}

22. Brazilian Peppertree

The Brazilian peppertree is a native of South America that was introduced to the United States in the mid-1800s for its ornamental value. Unfortunately, Schinus terebinthifolius is an aggressive spreader, producing abundant seed and forming dense stands of vegetation which crowd out native plants.³⁶

23. Camphor Tree

The camphor tree of East Asia was first introduced to the U.S. in the late 1800s for its ornamental and economical value. With the help of native birds dispersing the abundant seed, Cinnamomum camphora has escaped cultivation to become invasive.

A single tree can produce around 100,000 seeds per annum.¹⁴

24. Catclaw Mimosa

Mimosa pigra is a native of Central and South America and Mexico. It is shrublike in its growth habit but can reach heights of 20 feet.

The catclaw mimosa has become naturalized in Florida and Hawaii. It thrives in riparian habitats where the climate is subtropical to tropical.²³

It is listed on the Federal Noxious Weed List.

25. Chinaberry

Chinaberry is a mid-sized deciduous tree native to Southeast Asia. Introduced in the late-1700s and cultivated for its medicinal properties, fuel, shade, and aesthetics, Melia azedarach has expanded its range to include much of the southern U.S. The chinaberry is a highly successful reproducer, spreading seeds by birds.

It is also able to regenerate from root suckers after being cut.⁴⁹

26. Chinese Privet

Ligustrum sinense is a small tree or shrub growing up to 30 feet. Introduced from Asia in the mid-1800s, the Chinese privet was often planted in hedgerows and borders.

Upon escaping cultivation, however, it was noted to spread rapidly, becoming invasive across the Southeastern United States. It outcompetes native vegetation and modified local ecosystems.⁶⁷

27. Chinese Tallow Tree

The Chinese tallow tree, native of China and Japan, is among the most invasive trees in the United States. Also known as the popcorn tree, Triadica sebifera was originally valued for its aesthetic value and its oils.

The Chinese tallow tree is a fast grower, and it is highly pest-resistant outside its native zone, making it very competitive wherever it grows. It decreases natural diversity and alters the chemistry of the soil it grows in.¹⁰

28. Melaleuca

Melaleuca quinquenervia is another plant that is listed on the Federal Noxious Weed List. It is a large, evergreen tree that thrives in wetland areas, such as the Everglades, where it has essentially smothered out acres upon acres of native vegetation.

This native of Oceania is now listed as invasive in the states of Texas, Florida, and South Carolina, as well as Massachusetts.^47,48

29. Persian Silk Tree

Albizia julibrissin is commonly known as the mimosa tree or the Persian silk tree. Introduced to the U.S. from China in the mid-1700s, the mimosa has remained a popular ornamental tree.

It is a smaller deciduous tree in the pea family, and like many of its Fabaceae relatives, produces abundant seed and root shoots. The Persian silk tree has a pleasing aroma and aspect, but it easily escapes cultivation and is not recommended.²

30. Paper Mulberry

The paper mulberry (Broussonetia papyrifera) is so named because its wood is used to make paper and cloth in its native regions. Although this species can grow to more than 30 feet, it has a mounding, shrub-like habit.

Paper mulberry rapidly invades disturbed sites, and it is readily spread by wildlife which consumes its fruits. It also produces root shoots to form dense growth and colonies.⁸

The above list is only a small sampling of the total number of invasive trees in the American South. Due to its unique (among contiguous U.S. states) subtropical to tropical climate, the state of Florida is home to m of the country’s invasive plants.

In 2017, the Florida Exotic Pest Plant Council (FLEPPC) reported that there were around 1,400 non-native plant species in the state, and more than 10% of those exotic species had escaped cultivation and become established in the wild. At the time of reporting, there were 79 invasive plant species across the state.^54,66

Why Are Mulberry Trees Illegal?

The red mulberry tree (Morus rubra) is native to the Northeastern U.S. and grows as far south as Texas and Florida, but it and other members of the Morus genus have developed a bad reputation. Despite the many known benefits of mulberry, several large cities, including Las Vegas, El Paso, and Tucson have banned the mulberry tree, but why are mulberry trees illegal in these areas?

Mulberry trees are banned in some urban areas due to 1) allergic reactions related to inordinate amounts of pollen production, 2) staining from the juice of the abundant fruits, and 3) walkway, infrastructure, and pipe damage from sprawling root systems.⁷⁰

What Types of Trees are Invasive Species in the United Kingdom?

Some types of trees that are considered invasive in the United States are also invasive on the other side of the Atlantic Ocean in the United Kingdom (UK).

At the same time, there are also trees which are native to the U.S. and have serious invasive potential in the UK.

According to the Royal Horticultural Society (RHS), any tree listed on the EU Regulation on Invasive Alien Species are treated as invasive species in the UK.³¹ The handling of invasive tree species in the UK is addressed in the Wildlife and Countryside Act 1981 and related legislation.

*Information on invasive trees compiled from multiple sources.^{9, 19, 30, 31}

Chinese Tallow Tree

Triadica sebifera, the Chinese tallow tree, while not present in all regions of the UK, is recognized by the EU as posing great harm to native habitats. The EU has adopted a ban on the sale of, planting of, breeding of, or keeping of Chinese tallow seeds or plants.¹³

32. Eastern Baccharis

Baccharis halimifolia is technically a shrub, but it can grow to heights of around 20 feet. This plant is a North American native that has become established in several European countries, demonstrating its ability to spread and dominate local ecosystems.

It produces dense thickets of growth and abundant seed.¹⁷

33. Golden Wreath Wattle

Acacia saligna, the golden wreath wattle, is a large shrub or small tree. It is a native Australian plant with nitrogen-fixing abilities that encourage and support other non-native growth.

It is fast-growing, and evergreen, with a weeping form.¹

Mesquite

Prosopis juliflora is a species of mesquite which is native to Mexico and Central America but has become invasive on multiple continents. Its deep roots outcompete natives for nutrients and water and can create additional issues.⁵⁰

Tree-of-Heaven

The China-native Tree-of-Heaven, Ailanthus altissima, has been introduced to many countries besides the United States. In fact, it has made its way into a large number of European countries, including the UK.

Its adaptability and competitiveness make it a problematic species in any non-native territory.⁶²

Invasive Tree Types by Region in the UK

There are not nearly as many invasive tree types identified in the UK as there are in the US, and the UK is more troubled by various invasive shrub and aquatic plant species. The following species are noted as problematic, or potentially problematic, in various regions of the UK.

England and Wales

Various Cotoneaster and Rhododendron species are problematic in the UK, and two species that plague England are the hollyberry cotoneaster (Cotoneaster bullatus) and the yellow azalea (Rhododendron luteum).³¹

The hollyberry cotoneaster (Cotoneaster bullatus) is a native East Asian shrub or small tree which threatens native habitats such as limestone cliffs and heathlands. Cotoneaster spreads quickly, developing extensive root systems and dense growth.⁴²

The yellow azalea (Rhododendron luteum) is another deciduous shrub, but this one is native to Eastern Europe. It has become naturalized in parts of the UK where it is listed as a Schedule 9 species, making it illegal to plant the species in the wild or allow its spread into the wild.⁷³

Northern Ireland

Northern Ireland is also threatened by Rhododendron and Cotoneaster spp., but the butterfly bush and salmonberry are other species to watch out for. The butterfly bush (Buddleja davidii) is a fast-growing shrub that can reach heights of 12 feet.

It is native to Asia, but is opportunistic and readily establishes itself in both natural and disturbed areas, disrupting native ecosystems.¹¹

Salmonberry, Rubus spectabilis, is another mid-size shrub. This one is native to North America, specifically the west coast.

It is problematic in the UK because it has a suckering habit, spreading through rhizomes, which can form large and dense thickets of growth.⁷⁹

Scotland

Various problematic species have garnered attention in the UK, with giant hogweed and Japanese knotweed prime among them. There aren’t many trees of note appearing to cause problems in Scotland, but Rhododendron ponticum is a different story.

Rhododendron ponticum is an evergreen shrub which can grow to be a small tree if it lives long enough. It produces root suckers and prolific seed, leading to dense growth which chokes out native vegetation.

This species is native to southern Europe and southwest Asia, but it has become established throughout the U.K. It poses particular challenges in Scotland, where it threatens Scotland’s Rainforest.⁴¹

Is the Tree of Heaven Invasive?

The Tree-of-Heaven, Ailanthus altissima, is an invasive tree species that is also known as the “stinking sumac” for its pungent odor. Tree-of-Heaven is native to China but was introduced to the U.S. in the 18th century for ornamental purposes.

It is extremely fast-growing, highly reproductive, and has excellent defense mechanisms to ward off predators and competing plant life.

Combined, these characteristics make it one of the most invasive tree types.^63,64

How Are Invasive Plants Controlled?

Controlling an established population of invasive plants can be quite a challenge given the rapidity in which they grow and spread. For this reason, it is extremely important for people to pay very close attention to what they are planting, nurturing, and cultivating on their property.

Invasive plants should never be planted intentionally on private or public property, so consult a local expert when the identity of a plant is in doubt.

There are several methods for addressing invasive plants, such as introducing natural pests of the plants, manual or mechanical removal, and herbicides. In the case of invasive trees, removal may be even more challenging due to the size of individual specimens.

Removing a large tree safely requires time, as well as the appropriate tools and skillset. Eliminating invasive trees is a job in and of itself, but it is also critical to monitor and limit their spread to other locations.

Seeds and fruit may be carried long distances on the wind or by wildlife. Removing the fruits of the trees before they are able to ripen can restrict the tree’s reproductive success.

Of course, this strategy is greatly limited by the size of the tree and is much more manageable for very small tree specimens such as orchard fruit trees.

Areas with dense invasive growth may be treated with prescribed burns and replenished with native seeds. This method requires a professional.⁵⁸

Examples of Exotic Trees That Are Non-Invasive?

Exotic plants have been introduced to the United States for many different reasons. Some of the primary motivations for cultivating non-native plants are for food crops, ornamental value, and economic potential.

Many of the exotic trees which now have populations in this country became established when they escaped cultivation.

As mentioned at the start of this article, all invasive trees are exotic, but not all exotic trees are invasive. In fact, there are probably more non-invasive exotic trees than invasive ones, and some readers will be surprised to learn that the following common trees are not native to the United States.¹⁵

1. Apple Tree (Malus sylvestris)
2. Black Mulberry (Morus nigra)
3. Black Poplar (Populus nigra)
4. Carolina Poplar (Populus x canadensis)
5. Crape Myrtle (Lagerstroemia indica)
6. English Hawthorn (Crataegus oxyacantha)
7. Fig Tree (Ficus carica)
8. Garden Plum (Prunus domestica)
9. Mountain Ash (Sorbus aucuparia)
10. Oleander (Nerium oleander)
11. Peach Tree (Prunus persica)
12. Scotch Pine (Pinus sylvestris)
13. Weeping Willow (Salix babylonica)
14. White Mulberry (Morus alba)
15. White Willow (Salix alba)

Invasive species are problematic because they compete with native species for resources and alter local ecosystems. Invasive trees are often fast-growing, shading out surrounding vegetation.

Understanding the danger of invasive tree types and knowing how to identify them is critical to protecting native habitats.

Frequently Asked Questions About Invasive Tree Types