A highly poisonous invasive plant capable of killing humans, livestock, and wildlife is spreading rapidly across roadsides, farm-field margins, drainageways, and even wetlands throughout Wisconsin and Minnesota, Applied Ecological Institute (AEI) warned today. Poison hemlock (Conium maculatum), every part of which is toxic, now forms dense colonies four to twelve feet tall along travel corridors, including a large stands recently documented in Barron County, Wisconsin, and extensive infestations along both the Wisconsin and Minnesota state lines bordering fields near the St. Croix River.

Senior ecologist Steven Apfelbaum, founder of AEI, says the pattern of spread is unmistakable and increasingly urgent. “These colonies march outward from mowed road shoulders, ditches, and field edges, then push into drainageways and low wetland ground,” he said. “Wherever the soil is disturbed, and the sun reaches the ground, poison hemlock moves in, and native plants disappear beneath it. We are watching a genuinely dangerous plant convert ordinary roadsides into hazards.”