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POISON HEMLOCK IS DEADLY TOXIC. Conium maculatum contains potent piperidine alkaloids, including coniine, throughout the plant. Leaves, stems, flowers, seeds, and roots can all be poisonous, and dried plant material remains dangerous. This is not a home medicinal herb and should never be made into tea, tincture, powder, extract, or experimental preparation.
Identification
Poison hemlock is a tall member of the carrot family. Mature plants commonly have smooth, hollow, hairless green stems marked with irregular purple or reddish blotches. Leaves are finely divided and fern-like. Numerous small white flowers form umbrella-shaped clusters. The foliage and stems may have an unpleasant or musty odor when crushed.
Dangerous Look-Alikes
Misidentification is one of the greatest risks. Poison hemlock can be confused with edible or useful members of the carrot family, including wild carrot, parsley relatives, chervil relatives, and other white-flowering plants. Never rely on a phone app, flower color, or a single feature when identifying an Apiaceae plant for food or medicine.
Wild carrot generally has hairy stems, while poison hemlock stems are characteristically smooth and purple-blotched, but no single trait should be used alone. If there is uncertainty, do not taste or ingest the plant.
How Poisoning Happens
Poisoning most often follows accidental or intentional ingestion, including cases where the plant was mistaken for an edible species. Livestock can also be poisoned. The alkaloids interfere with nervous-system function and neuromuscular transmission.
Poisoning Symptoms
Possible effects include nausea, vomiting, abdominal pain, salivation, tremors, weakness, confusion, slowed or rapid heart rate, seizures, progressive muscle paralysis, and respiratory failure. Severe poisoning can be fatal because the muscles needed for breathing become paralyzed.
Suspected ingestion is an emergency. Contact Poison Control or emergency medical services immediately. Do not wait for symptoms and do not attempt a home antidote.
Handling & Removal
Wear gloves, long sleeves, and eye protection when removing established plants, especially when cutting or digging large stands. Wash exposed skin and tools afterward. Avoid unnecessary contact with sap and plant debris.
Do not burn poison hemlock. Burning poisonous plant material can create additional exposure hazards. Prevent seed formation, bag or dispose of plants according to local invasive-plant guidance, and keep removed material away from children, pets, and livestock.
Legal & Noxious-Weed Status
Regulation varies by jurisdiction. In Washington State, poison hemlock is listed as a Class B noxious weed and is also covered by the state's plant quarantine. State guidance prohibits transporting, buying, selling, offering for sale, or distributing the plant or its regulated plant parts within Washington. Other states and local governments use different weed classifications, so landowners should check current local rules.
Historical Context
Poison hemlock is historically associated with ancient Greece and the execution of Socrates. It has also appeared in older medical writings, but historical experimentation does not make it an appropriate modern herbal remedy. Its narrow margin between biological activity and life-threatening poisoning makes home internal use unacceptable.
Garden & Property Safety
Because it produces large numbers of seeds and readily colonizes roadsides, pastures, ditches, vacant land, and disturbed soil, early identification and removal before seed set are important. Anyone dealing with a large infestation should use local extension or noxious-weed guidance rather than improvising.
Educational information only. Suspected poison-hemlock exposure or ingestion requires immediate professional poison-control or emergency medical guidance.