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6 dangerous weeds were confirmed in new areas of Minnesota in 2020

One highly poisonous plant and five others known to outcompete native plants have been discovered in nine counties.
Poison hemlock, a highly poisonous plant to humans and animals, was found in three more counties in 2020.

Poison hemlock, a highly poisonous plant to humans and animals, was found in three more counties in 2020.

The Minnesota Department of Agriculture (MDA) identified six species of dangerous weeds in nine counties in 2020, including a "highly poisonous" plant that was found in three counties in southern Minnesota for the first time.

MDA is required to inform the public when a plant on Minnesota's Noxious Weed List, which are plants that aren't currently known to be in Minnesota or are not widely established here, are found in counties for the first time. 

The plants on the noxious weed list can be harmful to public health, the environment, public roads, crops, livestock or property. That's why state law requires the landowner to destroy all parts of the plant (above and below-ground) when it is discovered. 

In a news release Monday, the MDA said last year it confirmed six species of weeds on the list in nine counties. They are: 

Poison hemlock

Poison Hemlock plant

Poison hemlock, which was found in Steele, Watonwan and Waseca counties, is a highly toxic plant that looks similar to wild carrot and grows in moist areas and along rights of way, MDA says.

This plant is "highly poisonous" to humans and livestock, so no part of the plant should be ingested and people should use gloves, wear long sleeves and pants and closed-toe boots when working with an infestation. Symptoms of poison hemlock intoxication include nervous trembling, salivation, pupil dilation, a rapid and weak pulse, and eventually a coma or death.

The plant also grows in dense patches and displaces native vegetation. 

Poison hemlock has been reported in several Minnesota counties, mostly in the southern half of the state. See a map here. The Minnesota Department of Natural Resources website also has additional information on the poisonous plant.

The plant was added to the state's eradicate list in 2018. 

Common teasel

Comon teasel flower

Common teasel, which was found in Dakota and Olmsted counties, is a short-lived perennial with spiny, stiff flower heads that prefer sunny, open habitats like roadsides or pastures. 

The plant forms large dense stands that outcompete desirable plant species, causing a reduction in wildlife forage, habitat, and species diversity. 

It was added to the state's eradicate list in 2012. 

Cutleaf teasel

Cutleaf Teasel plant

Cutleaf teasel, which was found in Martin County, are closely related to the common teasel and also choke out desirable plants, reduce forage, wildlife habitat and species diversity. 

It was added to the state's eradicate list in 2012. 

Dalmation toadflax

dalmation toadflax plant

Dalmation toadflax, which was found in Cass County, is a perennial with yellow flowers that grow in sandy or gravelly soils. 

This plant outcompetes desirable species to form large monocultures. Infestations in the western United States have led to reduced livestock production, land values, biodiversity and wildlife habitat. 

It was added to the state's eradicate list in 2012, and there has been a confirmed infestation in Kittson County. 

Meadow knapweed

meadow knapweed

Meadow knapweed, which was found in Norman County, is a deep-rooted perennial with pink flowers that grows in sunny, wet conditions. 

This plant outcompetes other plants, reducing forage, wildlife habitat and species diversity. 

It was added to Minnesota's eradicate list in 2013.

Palmer amaranth

Palmer Green

Palmer amaranth, which was found in Winona County, is a high-profile noxious weed of row crops. 

This plant competes "aggressively" with crops and grows quickly, with MDA noting yield losses have been up to 91% in corn and 79% in soybean. 

It was added to the eradicate list in 2015.

To report a noxious weed, contact the MDA's Arrest the Pest hotline via email at or by calling 1-888-545-6684.

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