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. Author: Feb 8, 2021 Poison hemlock, a highly poisonous plant to humans and animals, was found in three more counties in 2020. Minnesota Department of Agriculture 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.