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Description
Poison Hemlock can grow to 6 feet or more in height. It has leaves and white flowerheads resembling those of parsnips, carrots, and water hemlock. It has a fleshy, white taproot, a main stem with characteristic light red spots and a disagreeable smell. All plant parts are poisonous. However, the seeds contain the highest concentration of poison. The conium alkaloids are volatile and can cause severe reactions when inhaled.
Habitat
Poison Hemlock is native to Europe and the Middle East. This plant is usually found in disturbed areas around culverts and roadside ditches, but it occasionally invades native habitats.
Risk Management
Poison hemlock is not known to normally cause skin rashes or allergic reactions when handled, but due to the extreme toxicity of this plant when ingested, good hand-washing is recommended after mowing or working around this plant. Do not dispose of plants within livestock pastures.
Control
Poison Hemlock can spread quickly in low-lying roadside areas and fields, posing a threat to humans and livestock. Spot treatments of actively growing plants with glyphosate, 2,4,D or dicamba is reportedly effective for control, especially if applied during the first year of growth when plants are in the vegetative rosette stage. Apply herbicides in accordance with the label.
The timely mowing of flowering plants before they go to seed will also help reduce the spread of Poison Hemlock since the plant is biennial and will die after the second season of growth.