Exotics

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Natives Vs. Exotics

An exotic plant is a species that has been introduced into a new environment. An invasive plant is one whose population begins to grow to the extent that it displaces other species in that area. It is important to note that not all exotic plants are invasive. Traditional annual flowers, such as marigolds and impatiens, are not native to NJ but are not naturalized, or reproducing on their own. Therefore, they are no real threat to natural systems.

Plants that are both exotic and invasive pose a major threat to biodiversity in all of NJ. In fact, they are the second greatest threat to biodiversity worldwide, second only to loss of habitat. They have been introduced to NJ for various reasons, both intentionally and accidentally, and have become naturalized. Invasive species have an extremely aggressive growth pattern, often forming dense stands or carpets, out-competing native plants which wildlife rely on for food and cover. They are often found to chemically alter soil properties in their favor, which further decimates native plant and animal populations. People are often unaware that these plants are not indigenous to our area, let alone threatening our native ecosystems. To compound the problem, many nurseries are still selling invasive plants. It is important not to plant these species in your yard or garden. If you already have any of these plants growing on your property, we encourage you to remove them and plant natives in their place.

One of URWA's stewardship initiatives is to remove invasive species from our properties, replacing them with NJ native vegetation. Our stewardship link has more information on current projects we are undertaking.

Information on the most common invasive species found in our area is detailed under the plant list link at left. If you have questions about any of this information, please contact us.

For additional information, please visit the USDA plant database.

Plant List

When choosing plants to landscape an area, native plants, which are readily available at most nurseries, should be chosen over non-native and invasive types. As a general rule, any plant described as Japanese, Oriental, English, etc. is obviously not native to North America and should be avoided. For instance, instead of choosing Japanese wisteria, utilize American wisteria.

Whenever available, the native variety of a plant should be used instead of the introduced, even if the plant is not considered invasive. For instance, instead of planting the introduced Kousa dogwood (Cornus kousa), consider the wide selection of native dogwoods such as flowering (Cornus florida) or alternate leaf (Cornus alterniflora).

Below is a list of the most common invasive plants found in NJ. Be aware of plant names while shopping at your local nursery and avoid these species. These plants should not be included in your landscapes and should be removed if they are already there. Some of the species listed are not those that would be used in landscapes but have become naturalized in backyards, along roadsides and in wild areas. They fit the traditional definition of weeds and should be treated accordingly. If you notice any of the invasive species growing, remove them as soon as possible to prevent them from spreading further. To the best of your ability, attempt to remove them before seeds or berries are apparent.

If you are aware of invasive plants not included on our list, please contact Melissa Almendinger (melissa (at) urwa (dot) org) so we may offer the most current information.

Native landscape plants are listed, according to similarity in growth pattern to the invasives. There are an abundance of native plants to our area that were not included on this list. Listed are plants that were found to be commonly available as nursery stock. Those marked with an asterisk (*) are threatened and/or endangered in NJ.

When questioning the nativity of a species not listed, please visit the USDA plant database.

Invasive Trees	Scientific Name	Native Trees	Scientific Name
Norway Maple	Acer platanoides	Sugar Maple	Acer saccharum
Black locust	Robinia pseudoaccacia	Red Maple	Acer rubrum
Tree of heaven	Ailanthus altissima	Oaks	Quercus sp.
Princess tree	Pawlonia tomentosa	Black gum	Nyssa sylvatica
		River birch	Betula nigra
		Sycamore	Platanus occidentalis
		Bottlebrush Buckeye	Aesculus parvifolia
		Native Small Trees
		Flowering dogwood	Cornus florida
		Witchhazel	Hammamelis virginiana
		Black cherry	Prunus serotina
		Downy serviceberry	Amelanchier arborea
		Shadbush	Amelanchier canadensis

Invasive Shrubs	Scientific Name	Native Shrubs	Scientific Name
Japanese barberry	Berberis thunbergii	Chokecherry	Aronia arbutifolia
Burning bush	Euonymous alatus	Redosier dogwood	Cornus sericea
Chinese privet	Lingustrum vulgare	Alternate leaf dogwood	Cornus alternifolia
Japanese spirea	Spirea japonica	Sweetshrub	Calycanthus floridus
Amur honeysuckle	Lonicera maackii	Inkberry holly	Ilex glabra
Tartarian honeysuckle	Lonicera tartarica	Winterberry holly	Ilex verticillata
Morrow’s honeysuckle	Lonicera morrowii	Arrowwood	Viburnum dentatum
Russian olive	Eleagnus angustifolia	Nannyberry	Virburnum lentago
Autumn olive	Eleagnus umbellate	Sweet pepperbush	Clethra alnifolia
Orange eye butterfly bush	Buddleja davidii	Shrubby cinquefoil	Potentilla fruticosa
Multiflora rose	Rosa multiflora	Eastern Redbud*	Cercis canadensis*
		Bayberry	Myrica pennsilvanica
		Rhododendron	Rhododendron maximum
		Swamp azalea	Rhododendron viscosum
		Highbush blueberry	Vaccinium corymbosum
		Mountain laurel	Kalmia latifolia
		American fly honeysuckle*	Lonicera canadensis*

Invasive Grasses	Scientific Name	Native Grasses	Scientific Name
Chinese Silver Grass	Miscanthus sinensis	Switch grass	Panicum virgatum
Pampass grass	Cortaderia selloana	Indian grass	Sorgastrum nutans
Japanese stilt grass	Microstigium vimineum	Wild Oats	Chasmanthium latifolium
		Sheep’s Fescue	Festuca ovina
		Blue Fescue	Festuca ovina glauca
		Creeping Red Fescue	Festuca rubra subspecies trichophylla
		Spreading Red Fescue	Festuca rubra subspecies rubra
		Chewings Fescue	Festuca rubra subspecies commutata
		Little Bluestem	Schizachyrium scoparium
		Prairie Dropseed	Sporobolus heterolepsis

NOTE: These native grasses all perform well at low fertility. Click on lawns for more information.

Invasive Perennials	Scientific Name	Native Perennials & Groundcovers	Scientific Name
Purple loosestrife	Lythrum salicaria	PERENNIAL
Lesser celandine	Ranunculus ficaria	Blue flag iris	Iris versicolor
Garlic mustard	Alliaria petiolata	Blackeyed susan	Rudbeckia hirta
Mugwort	Artemisia vulgaris	Browneyed susan	Rudbeckia triloba
Japanese knotweed	Polygonum cuspidatum	Virginia bluebells	Mertensia virginica
Canada thistle	Cirisium arvense	Joepyeweed	Eupatorium maculatum
Invasive Groundcovers	Scientific Name	White Wood Aster	Aster divaricatus (sometimes listed Eurybia divaricata)
English ivy	Hedera helix	Calico Aster	Aster laterifloru
Periwinkle (Vinca)	Vinca minor	Big Leaved Aster*	Aster macrophyllus
Periwinkle (Vinca)	Vinca major	Wild Ginger	Asarum canadense
		Alumroot	Heuchera americana
		Roundleaf Alumroot	Heuchera cylindrical
		Maple-leaved Alumroot	Heuchera villosa
		Wild Lily of the Valley or Canada Mayflower	Maianthemum canadense
		Creeping Mint	Meehania cordata
		Clumping Foamflower	Tiarella wherryi
		Running Foamflower	Tiarella cordifolia
		EVERGREEN	Scientific Name
		Alleghany Spurge	Pachysandra procumbens
		Barren Strawberry	Waldsteinia fragarioides
		FERN	Scientific Name
		Hay Scented Fern*	Dennstaedtia punctilobula
		Marginal Shield-fern	Dryopteris marginalis
		Christmas Fern (evergreen)	Polystichum acrostichoides
		New York Fern	Thelypteris noveboracensis

*can be tried as a mulch substitute for new trees

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Upper Raritan Watershed Association
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