duluth-cisma@stewardshipnetwork.org
Many Minnesotans are becoming more aware of the ecological harm that native plants can do. It may come as a surprise that some invasive plants can also hurt people who come into contact with them. The Minnesota Department of Agriculture warns that many of the invasive plants listed on Minnesota’s Noxious Weed List (https://www.mda.state.mn.us/minnesota-noxious-weed-list) can be harmful or toxic to humans and animals, as well as to our ecosystems. For example, sap from wild parsnip (Pastinaca sativa), an invasive plant commonly found on roadsides and grasslands, causes burns and blisters to skin. Wild parsnip is related to wild carrot, also known as Queen Anne’s lace (Daucus carota), which can also cause uncomfortable skin irritation.
Common and cutleaf teasels (Dipsacus fullonum and D. laciniatus), hooked hair hops (Humulus japonicus), and Canada and plumeless thistles (Cirsium arvense; Carduus acanthoides) all have sharp prickles on the stems and leaves that can cause painful scratches and inflammation.
Several noxious weeds can be toxic if ingested. Grecian foxglove (Digitalis plantaginaceae) toxicity can cause abnormal heart rhythms and can be toxic to livestock. Poison hemlock (Conium maculatum) is toxic if ingested or if its sap is absorbed through skin. Common tansy (Tanacetum vulgare) toxicity can cause liver and brain damage.
Invasive plants don’t just affect humans and livestock. Two species on the noxious weed list are also toxic to monarch butterflies. Black and pale swallow-wort (Cynanchum louiseaeare; Cynanchum rossicum) are two vining milkweeds that are found in very small populations in Minnesota. Though they are related to our native milkweeds, they are toxic to monarch caterpillars, and eggs that are laid on their leaves will not survive.
You can learn more about invasive plants from the noxious weed list at the Minnesota Department of Agriculture’s Noxious Weed List webpage. If you need help identifying a species, you can create a report through the Department of Agriculture’s Report A Pest form (https://www.mda.state.mn.us/reportapest) . For information about livestock toxicity, the University of Minnesota maintains a webpage of Plants Poisonous to Livestock (https://extension.umn.edu/forage-harvest-and-storage/plants-poisonous-livestock).
You can help preserve Minnesota’s rich ecological diversity by being a good land steward, dealing with invasive plants on your land promptly and carefully.
