Invasive Plants in the Landscape

What are invasive plants?

For a complete definition and description, visit the Conservation pages of the NEWFS web site.

For the most part, invasive plants are non-native plant species that are ‘overachievers' - so successful and aggressive that they spread into natural areas and become dominant or disruptive to those systems. They are habitat generalists that grow well under a variety of conditions, producing prolific amounts of fruit or seed, or spread in other aggressive ways such as underground runners or climbing vines. The seeds of many invasive plants are carried by birds, wind, or water currents, allowing them to spread far beyond the area of original introduction. Once established in new areas, they take over and outcompete the native species. Invasive plants cause profound environmental damage.

I don't want to plant invasive plants, but I love the look of some of them. What can I plant instead?

Nurseries and garden centers offer many wonderful plants that can serve as alternatives for each invasive species used in horticultural applications. Underneath the list of ‘rogues' below is a short list of very desirable native species that are suggested instead. For hundreds more great choices, visit the Society's Native Plant Nursery List, or check with your local native plant provider.

Loosestrife is so pretty, but I've heard it is invasive. What could be the harm of something so beautiful?

Although some may enjoy seeing its bright purple flowers in the wetlands and along roadsides in summer, it is highly aggressive. One mature loosestrife plant may produce up to two million seeds a year that could easily become thousands of plants the next year. At a certain point it just overwhelms the other plant species in these wetlands, and the diverse animals depending on those other plants disappear. Once these ‘monocultures' develop it spells disaster for the ecosystem. Loosestrife, like most other invaders on this list, is an exotic plant introduced into an environment where it has no predators.

Poison ivy is taking over my garden. Does that mean it's an invasive plant?

To be ecologically responsible, our first concern is what is harming the natural environment. Although certain ‘thugs' such as poison ivy are a nuisance in the home garden or on trails where people walk, those species (called "explosive species") will not stop natural ecological processes to such as extent as to wipe out the biodiversity of an area. To be designated as an invasive species, a plant must be so aggressive it takes over the habitat of other species, eventually wiping them out and causing ecological and/or economic harm, even when light or water conditions change.

I saw burning bush for sale at my local home improvement store. If they sell it, it must be safe, right?

Sadly, no. Burning bush is a seriously problematic plant in the northeastern region of the United States , outcompeting other plants. Birds spread the seed into natural areas, causing problems there as well. It is commonly found in the nursery trade because it is so easy and inexpensive to grow. There are few laws about invasive plants at this time. Right now, staying informed about invasive plants to be avoided in your region is the best strategy. Although most nursery providers care about the earth and want to do the right thing, there are some plants that are sold in nurseries and other stores that should not be planted in the landscape. To make sure you know for sure, check the state lists at the NEWFS web site or check with your local native plant society.

The clerk at the store told me that this special new variety of burning bush isn't invasive. Is that true?

Unfortunately, that is not correct. This species has been designated invasive in central and southern New England , and should be avoided, as the new cultivars have been shown to revert back to their old invasive ways in the wild. Cultivars and subspecies are considered equally invasive. As far as we know, at this time there are no ‘safe' cultivars for any of the species on the list below.

If this plant is so bad, how come they just put in twenty shrubs at the new library in town?

Again, this is more about lack of good information. Those qualities that make a plant invasive also make them inexpensive to purchase and tough to kill! They would be good choices if they weren't so bad for the nearby natural areas. Now that you are well informed, please share your knowledge with others. Let the officials in your town know that you care about the message they are sending, and encourage them to more ecologically appropriate choices.

My favorite garden magazine recently recommended bittersweet for my holiday decorations. Isn't that an invasive plant?

You are absolutely correct. It is not safe for the environment to use bittersweet or the fruit or berries of any invasive plant in decorations or in any way in your landscape, even in their dry state. When used outdoors, birds eat the berries and distribute the berries. Even as an indoor decoration, disposal is a concern and displaying it encourages others to grow it without understanding the dangers. We recommend avoiding it completely!

I already have lots of invasive plants growing in my garden. What does the Society recommend I should do?

The Society looks at this from two points of view. From the broader ecological perspective, controlling invasive plants requires tremendous amounts of time and money, so with limited resources, we must choose our larger battles carefully, focusing on efforts that protect rare, pristine or unique habitats or plant populations. On the other hand, gardens and cultivated landscapes, especially those near natural areas, are prime sources of re-invasion of these problem species, so the more we remove in our own gardens, the better. Your own backyard is often the best place to start removing invasives, as you don't need to be concerned about permitting, and it is certainly close to home. You will be able to focus more effectively on your backyard than on a large natural area.

Invasive, non-native plants have become a major threat to the integrity of plant communities and native habitats around the country. Different plants are problematic in different areas, so it is important to learn the list in your state. For Massachusetts, these plant lists may be found at on NEWFS web site. Lists for the rest of New England will be posted soon. If you are outside of New England, NEWFS has a listing of native plant societies where you may be able to find more information.

Native Alternatives to a “Dirty Dozen” Invasive, Non-native Plants

These common invasive plants should not be planted in any form in the northeastern region of the U.S. as they are all declared highly invasive and dangerous for the environment: These invasive non-native plants commonly used in landscape plantings should no longer be used in any form, since no known cultivars have been proven safe and completely sterile. The list is followed by some suggested North American native species that are appropriate substitutes in the northeastern region of the U.S. Feel free to use your imagination, other plant lists on the NEWFS website, and the knowledge of the nursery staff where you shop, to think of other beautiful substitutions.

[To help you identify these plants, NEWFS has published resources, including images, on the Conservation pages.]

Norway maple (Acer platanoides)

Japanese barberry (Berberis thunbergii)

Autumn-olive ( Elaeagnus umbellata)

Burning bush or winged euonymus (Euonymus alatus)

European buckthorn (also known as glossy or common buckthorn) (Frangula Alnus formerly known as Rhamnus frangula)

Yellow iris (Iris pseudacorus)

Amur, Morrow's, Bell 's, tatarian, and other shrub honeysuckles (Lonicera maackii, L. morrowii, L. tatarica, L. x bella )

Japanese honeysuckle (Lonicera japonica)

Purple loosestrife (Lythrum salicaria)

Japanese knotweed; Japanese bamboo (Polygonum cuspidatum, Fallopia japonica and its varieties)

Multiflora rose (Rosa multiflora)

Invasive, non-native plants have become a major threat to the integrity of native habitats around the country and the world. Next to global development, it is the leading cause of the loss of native species! The New England Wild Flower Society works extensively with other regional agencies to share information about control of non-native invasive plants in New England , and organize management activities in the field to protect rare species and unusual habitats from this invasion. The Society trains volunteers and organizes field programs focusing on this work. Click here to learn more about the programs.

Although the vast majority of non-native species in our gardens are not a problem, a relative few have become huge problems , like a tidal wave rolling over the landscape. Tremendous efforts are being focused on controlling these plants. One of the characteristics of these species is their ability to spread copious quantities of seeds by birds, wind or water. Even seeds of selected cultivars are a problem, since they also spread and often revert back to the wild forms of the species. As landscapers and gardeners, we can do our part by not planting these species or their cultivars in new or existing landscapes, as well as supporting efforts to remove them from both cultivated spaces and wild areas.

The following “Dirty Dozen” is a selection of invasive non-native plants commonly used in landscape plantings that should no longer be used in any form, along with some suggested North American native species that are appropriate substitutes in the northeastern region of the U.S. Feel free to use your imagination, other plant lists on the NEWFS website, and the knowledge of the nursery staff where you shop, to think of other beautiful substitutions.

Norway maple (Acer platanoides)

Tree in upland sites, growing in full sun to part-shade.

Alternatives for specimen tree and street tree:

Acer rubrum (Red Maple)—same general leaf shape, good fall color
Acer saccharum (Sugar Maple)—same leaf shape, good fall color
Cladrastis kentuckea (Yellowwood) –white flowers, rich yellow fall color
Liquidambar styraciflua (Sweetgum) –similar leaf shape, brilliant fall color
Liriodendron tulipifera (Tulip Poplar)—similar large leaf, with beautiful magnolia-like flower
Quercus palustris (Pin Oak) –tolerant of various conditions

Japanese barberry (Berberis thunbergii) `

Shrub in upland or wetland sites, growing in full sun to shade

Alternatives for hedges, fall color, fruits for birds:

Ilex verticillata (Common Winterberry)—dwarf forms similar in character, with bright red winter fruits
Itea virginica (Virginia Sweetspire) –fragrant white flowers, rich red fall color
Myrica pensylvanica (Bayberry) –yellow flowers, grey fruits wonderful for birds
Vaccinium angustifolium (Lowbush Blueberry) –wonderful flowers, fruits, fall color
Viburnum opulus var. americanum (= V. trilobum ) (American Cranberry Bush)—white flowers, yellow to red-purple fall color with good fruits for birds

Asiatic bittersweet or Oriental bittersweet (Celastrus orbiculatus)

Vine in upland sites, growing in full sun to part-shade

Alternatives for vines with interesting fruits, flowers or fall color:

Celastrus scandens (American Bittersweet)—same interesting fruit
Parthenocissus quinquefolia (Virginia Creeper)—great fall color

Autumn-olive ( Elaeagnus umbellata)

Shrub in upland sites, growing in full sun

Alternatives for hedges and attracting birds:

Aronia arbutifolia (Red Chokeberry)—white flowers, red-purple fall color, berries for birds.
Fothergilla gardenia or F. major (Fothergilla)—white flowers in spring, beautiful fall color.
Ilex glabra (Inkberry)—similar small leaves, but evergreen, with black fruits for birds
Myrica pensylvanica (Bayberry) –yellow flowers, grey fruits wonderful for birds
Prunus maritima (Beach Plum)—white flowers, beautiful purple fruits
Shepherdia canadensis and S. argentea (Silver buffalo-berry)—western US species with silvery foliage
Viburnum prunifolium (Possumhaw) –white flowers, fruits for birds, grey bark
Viburnum opulus var. americanum (= V. trilobum ) (American Cranberry Bush)—white flowers, yellow to red-purple fall color with good fruits for birds

Burning bush or Winged euonymus (Euonymus alatus)

Shrub in upland sites, growing in full sun to full shade.

Alternatives for fall color and compact habit:

Aronia arbutifolia (Red Chokeberry)—white flowers, red-purple fall color, berries for birds.
Clethra alnifolia (Summersweet) –white flowers, golden fall color
Cornus spp. (shrub dogwoods)—also colorful winter twigs, fruits for birds, big white flowers

Itea virginica (Virginia Sweetspire) –fragrant white flowers, rich red fall color

Lindera benzoin (Spicebush)
Vaccinium corymbosum (Highbush Blueberry)
Viburnum nudum (Witherod) –great fall color

Viburnum prunifolium (Possumhaw) –white flowers, fruits for birds, grey bark

European, glossy or common buckthorn ( Frangula alnus, Rhamnus cathartica Rhamnus frangula)

Shrub or small tree in upland, wetland, and coastal areas, growing in full sun to shade.

Alternatives for hedges and attracting birds:

See also suggested alternatives for Burning bush and Autumn-olive
Nemopanthus mucronatus (Mountain Holly) –good for moist sites, silken red fruits
Viburnum dentatum (Arrowwood) –white flowers, fruits for birds, great fall color
Viburnum lentago (Nannyberry) –white flowers, fruits for birds.

Consistant format—common and scientific names

Yellow iris ( Iris pseudacorus)

Herbaceous perennial in wetlands, growing in full sun to partial shade.

Alternatives for flowers at wetland edge:

Blue flag iris (Iris versicolor) —blue iris
Southern blue flag (Iris virginica) –blue iris with purple base of stems
Marsh marigold (Caltha palustris) —bright yellow flowers in early spring
Tickseed ( Coreopsis integrifolia )—yellow daisy flowers
Western skunk cabbage (Lysichiton americanum )—not readily available, but beautiful yellow arum flower in spring

Amur, Morrow's, Bell 's, Tatarian, and other shrub honeysuckles (Lonicera maackii, L. morrowii, L. tatarica, L. x bella )

Shrub in upland, wetland, and coastal areas, growing in full sun to shade

Alternatives for berries, screening, and fragrant flowers:

Aesculus parvifolia (Bottlebrush Buckeye) –upright flower spires
Amelanchier spp. (Serviceberry) –fragrant flowers, edible berries
Diervilla sessilifolia (Southern Bush Honeysuckle) –lush growth, bright yellow honeysuckle flowers
Diervilla lonicera (Northern Bush Honeysuckle)—bronzy new growth, bright yellow honeysuckle flowers

Ilex (deciduous spp.) (Winterberry) small, but fragrant flowers and bright red winter fruits
Itea virginica (Virginia Sweetspire) –fragrant white flowers, rich red fall color

Lonicera involucrata (Twinberry) –northern native, shrub honeysuckle with interesting fruits

Japanese honeysuckle ( Lonicera japonica)

Vine in upland, wetland, or coastal areas, growing in full sun to shade.

Alternatives for vines with berries or fragrance:

Lonicera ciliosa (orange honeysuckle) –orange flowers, spring to summer
Lonicera dioica (limber honeysuckle) –spring to early summer blooms, yellow honeysuckle flowers
Lonicera flava (yellow honeysuckle) –yellow, honeysuckle flowers spring to early summer
Lonicera sempervirens (trumpet honeysuckle) –deep orange flowers, blooms all summer

Purple loosestrife (Lythrum salicaria)

Herbaceous perennial in upland and wetland sites, growing in full sun to partial shade.

Alternatives for lavender flowers in summer

• Agastache foeniculum (giant blue hyssop)—spires of blue flowers (full sun only)

• Asclepias incarnata (swamp milkweed)—also great nectar plant, and host plant for monarch butterflies

• Eupatorium dubium (and E. purpureum) (Joe-pye-weed)-- also great nectar plant, esp. for butterflies

Japanese knotweed; Japanese Bamboo (Polygonum cuspidatum, Fallopia japonica and its cultivar ‘Variegata')

Herbaceous perennial to shrub-like in upland, wetland, and coastal sites, growing in full sun to shade

Alternatives for bigger, interesting foliage:

Asclepias purpurascens (purple milkweed)-showy summer flowers for sun
Asclepias speciosa (showy milkweed)— showy summer flowers for sun
Hibiscus moscheutos (swamp rose mallow)—sunny, moist sites
Polygonatum biflorum var. commutatum (giant Solomon's seal) –shade with white bell-like flowers
Saxifraga pensulvanica (swamp saxifrage)—shady, moist sites
Senna hebecarpa (northern wild senna)—yellow flowers, sun to part shade
Veronicastrum virginicum (Culver's root)- spires of pale pink flowers for sun

Multiflora rose (Rosa multiflora)

Shrub to vine-like in upland, wetland, and coastal sites, growing in full sun to shade.

Alternatives for climbing rose-like character and flower:

Rosa setigera (climbing prairie rose) –climbing and prodigious blooms
Rosa virginiana (Virginia rose)—pink flowers and bright red rose hips
Rosa carolina (Carolina pasture rose)—pink flowers and deep red rose hips
Rubus odoratus (flowering raspberry)—large pink flowers, thornless, large soft leaves, for dry areas and shade.