Do you have invasive non- native plants in your Michigan garden? The DNR and various conservation groups are again urging residents to root out and destroy certain plants that are not native and considered invasive or dangerous to our native plant ecosystems. Some of them you are probably familiar with, such as Autumn Olive and Purple Loosestrife. Some others on the list may amaze you.
According to the Michigan DNR these plants are:
- Norway Maple- Acer platanoides
- Tree of Heaven -Ailanthus altissima
- Black Alder -Alnus glutinosa
- Russian Olive- Elaeagnus angustifolia
- Black Locust- Robinia pseudoacacia
- Japanese Barberry- Berberis thunbergii
- Autumn Olive- Elaeagnus umbellata
- Glossy Buckthorn – Frangula alnus/Rhamnus frangula
- Privet – Ligustrum vulgare
- Amur Honeysuckle- Lonicera maackii
- Morrow’s Honeysuckle- Lonicera morrowii
- Tartarian Honeysuckle- Lonicera tatarica
- Bell’s Honeysuckle – Lonicera xbella
- Common Buckthorn- Rhamnus cathartica
- Black Jetbead – Rhodotypos scandens
- Multiflora Rose- Rosa multiflora
- Oriental Bittersweet- Celastrus orbiculatus
- Japanese Honeysuckle -Lonicera japonica
- Kudzu- Pueraria lobata
- Garlic Mustard Alliaria petiolata
- Narrow-leaved Bitter-cress Cardamine impatiens
- Spotted Knapweed- Centaurea stoebe/Centaurea maculosa
- Canada Thistle -Cirsium arvense
- European Swamp Thistle- Cirsium palustre
- Black Swallow-wort- Cynanchum louiseae /Vincetoxicum nigrum
- Pale Swallow-wort- Cynanchum rossicum /Vincetoxicum rossicum
- Leafy Spurge- Euphorbia esula
- Baby’s Breath- Gypsophila paniculata
- Giant Hogweed- Heracleum mantegazzianum
- Dame’s Rocket- Hesperis matronalis
- Lyme-grass- Leymus arenarius
- Purple Loosestrife- Lythrum salicaria
- White Sweet Clover- Melilotus alba
- Yellow Sweet Clover- Melilotus officinalis
- Japanese Stilt Grass- Microstegium viminium
- Wild Parsnip- Pastinaca sativa
- Reed Canarygrass- Phalaris arundinacea
- Phragmites -Phragmites australis
- Japanese Knotweed- Polygonum cuspidatum
- Giant Knotweed- Polygonum sachalinense
- Mile-a-minute Weed- Polygonum perfoliatum
- Narrow-leaved Cat-tail- Typha angustifolia
- Flowering Rush- Butomus umbellatus
- Water-hyacinth- Eichornia crassipes
- Hydrilla- Hydrilla verticillata
- European Frog-bit -Hydrocharis morsus-ranae
- Eurasian Water Milfoil- Myriophyllum spicatum
- Curly Pondweed- Potamogeton crispus
This is the list of plants that the MDNR and many Michigan nature groups want eliminated from Michigan. You are supposed to destroy these plants when you find them. It’s puzzling why some of the plants were included, especially those like Black Locust which are native plants. Others are plants like Norway maple, privet and barberry which are still widely sold in Michigan nurseries without any censure.
Many of our common garden plants are not native plants and some are quite invasive. Comfrey and the common daylily are two examples. Dandelions are non-native and an aggressively invasive plant we see daily in Michigan. They don’t make the list. Probably because the control of dandelions is such a big business we don’t want them to be eliminated entirely.
Baby’s Breath has invaded the Sleeping Bear Sand Dunes and that is why this species has entered the noxious plants list but although the government is spending thousands of dollars to remove it, little research has been done to see if it significantly alters the dune community.
Dames Rocket would be better classified as a wildflower. It does spread aggressively but its pretty flowers are a favorite of bees and butterflies. Many people grow it in their gardens to attract these pollinators. And it’s still included in wildflower seed mixes.
White Sweet Clover and Yellow sweet clover are common forage and cover crops grown in Michigan yet they also make the non-native invasive list. Crown vetch isn’t mentioned, but it’s non-native and definitely invasive.
Many forms of honeysuckle are listed as invasive- non-native plants. Amur Honeysuckle is listed as an endangered species in Japan. Most of the other honeysuckles are no more aggressive than Virginia Creeper, or Trumpet Creeper, both natives that give many homeowners more headaches than the honeysuckles do.
Japanese Barberries have many horticultural forms with purple or yellow foliage cultivars very commonly planted in Michigan. They are literally sold by the thousands in Michigan nurseries for landscaping, yet the MDNR wants them to be eliminated. Black Jetbead, (Rhodotypos scandens), with pretty white flowers and attractive black fruit is recommended by many arboretums as an under utilized landscape plant yet the MDNR wants it eliminated.
The Black Locust is listed by most references as a native northeastern tree and yet it’s listed as an invasive non-native. The tree is poisonous if livestock eat it but many native plants are. It’s a favorite tree of bees, although Black Locust honey can be poisonous too, but it has beautiful fragrant flowers. The wood is tough and rot resistant and the lumber is often used for woodworking. Why we are being urged to seek out and destroy this tree is a mystery. Honey Locust trees also spread aggressively but they don’t make the list. If any tree is to be listed as noxious it should be the yew, which is extremely poisonous and more likely to be found close to homes.
Norway Maples and Tree of Heaven are common inner-city trees because they are resistant to pollution and grow well in harsh city conditions. Yes, they are not native trees, but neither are Japanese Maples and Ginkgos. If we start removing non-native trees from the environment we will lose a lot of our shade and oxygen producers.
Some plants on the invasive list that people have mixed feelings about include Autumn Olive. Autumn Olive provides abundant berries for the birds in the hall. Those berries are also being used now in various human foods since they are so high in lycopene, an important anti-oxidant. In the spring the sweet smell of Autumn Olive fills the air and bees make one of the most delicious honeys there is from them. Yes they do clog fields, and resist efforts to control them but so do many other plants such as the Box Elder. .
Phragmites are called pampas grass (incorrectly) by many Michiganders and some go out of their way to keep the road commission from mowing them down. They generally grow in ditches or wet open areas. They don’t invade crops very often and don’t spread by seed. They don’t have many beneficial traits but then they don’t do much harm and many people enjoy looking at the fluffy plumes.
Purple Loosestrife once threatened to clog every Michigan wetland, but now that it has some disease and insect controls it’s not nearly as threatening. Whether we should continue to try and destroy it is debatable.
Water hyacinth would probably not survive a Michigan winter, most pond gardeners over winter it inside. There is some debate as to whether Narrow Leaved Cattail is native to North America or an early invader. It hybridizes with regular cattails readily. It should have no detrimental effects that regular cattails don’t have. Narrow leaved cattail flour is being studied as a remedy for inflammatory bowel problems.
There are some plants on the invasive list that gardeners wouldn’t miss and that everyone can agree are non -native invaders that should be destroyed. Garlic Mustard is one, it isn’t pretty, isn’t eaten by anything even deer, and since deer don’t eat it, it takes over the forest understory where the native plants are being decimated by deer. Let’s root it out and destroy it.
Another plant on the list, Spotted Knapweed, also has little value, and destroys hayfields and pastures. Giant Hogweed has an impressive stature and huge flowers which is the cause of it being brought into Michigan. However it’s a dangerous plant, causing third degree burns where the sap contacts human skin. It deserves elimination. Mile- a- Minute weed is also not pretty, has no wildlife use and strangles other plants. But it’s little different from Bindweed, which isn’t listed.
Canada Thistle is an important agricultural pest and despite the name is not native to North America. The biggest danger in urging people to destroy it is that it resembles some rare and threatened native thistles.
Many plants on the list would simply be considered weeds, of no major importance other than annoyance. Why are Narrow Leaf Bitter Cress and Lyme grass listed and Ground Ivy and Shepard’s Purse, both invasive non-native plants, are not?
If Michigan is serious about its noxious and invasive plant list then it should ban sales of plants on the list and have botanical gardens and arboretums remove them. People who have a privet hedge should be asked to remove it, as well as Oriental Bittersweet vines. It would probably be better if Michigan restricted its list to truly non-native and harmful plants. An eclectic assortment of plants, many of which have not been intensively studied to determine their effect on the environment, just doesn’t impress knowledgeable gardeners.
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To read more gardening articles by Kimberley Willis click on her name above.