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“Hemlock” can refer to several things. This guide covers poison hemlock (Conium maculatum), a highly toxic plant—not hemlock trees or water hemlock. If someone may have eaten it, seek urgent professional help rather than waiting for symptoms.
What does poison hemlock look like?
Poison hemlock is a biennial member of the carrot family (Apiaceae). The National Park Service describes it as commonly 2 to 10 feet tall, with fernlike, divided leaves and small white or yellowish flowers arranged in umbrella-shaped clusters. Its fruit is egg-shaped, with wavy ribs.
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Stems are typically hollow and ribbed, with purple streaks or blotches. These features can vary: a plant may lack conspicuous spotting at some life stages, so no single feature—or a plant-identification app—can certify that an unfamiliar plant is safe to eat. The NPS profile was prepared in 2010 and last updated April 29, 2016.
Poison hemlock is reported in disturbed places such as roadsides, field edges, ditches, marshes and meadows, often in moist or shaded settings. The NPS says it is naturalized in almost every U.S. state; that does not establish whether it is present at a particular property or job site.
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How can I tell it from wild carrot, wild parsnip or water hemlock?
These plants can resemble one another because they belong to the same family. Use the comparison for awareness, not for deciding that a wild plant is edible. Poison Control warns that characteristic spotting or odor may be absent at some growth stages, and lookalikes have been involved in foraging mistakes.
| Plant | Useful comparison clues | Important limit |
|---|---|---|
| Poison hemlock | Often has smooth, hollow stems with purple mottling, divided leaves and white flowers in umbrella-shaped clusters. | Appearance varies; those traits are not a safety test. |
| Wild carrot (Queen Anne’s lace) | The NPS notes a hairy stem and no purple stem mottling. | A resemblance to wild carrot does not make an uncertain plant safe to eat. |
| Wild parsnip | The NPS notes no purple stem mottling. | Do not identify by one stem feature alone. |
| Water hemlock | The NPS distinguishes it by a cluster of fleshy taproots. | It is a different poisonous plant; root appearance is not a reason to handle or taste it. |
Poison Control also lists angelica, cow parsnip, wild chervil and wild celery among plants that may be confused with poisonous species. If you forage, follow Poison Control’s advice: “Never eat an unknown plant or berry without verification from a clear field guide or someone with experience.”
Is poison hemlock poisonous to touch?
All parts—leaves, stems, fruit and roots—are poisonous if eaten. USDA Agricultural Research Service identifies coniine, gamma-coniceine and related piperidine alkaloids as toxic compounds. The supplied sources establish the danger of ingestion; they do not provide a basis for treating every brief skin contact as poisoning. Avoid handling the plant, keep it away from children, and wash up if contact occurs. Do not use hollow stems as whistles or toys.
What should I do if someone ate poison hemlock?
Get emergency professional advice immediately if ingestion is possible. Poison Control advises emergency evaluation, use of its online triage tool, or a call to a poison center. In the United States, its page lists 1-800-222-1222; follow current local emergency guidance if the person is seriously ill or having trouble breathing.
- Do not wait for symptoms to appear and do not try a home remedy.
- Tell responders what may have been eaten and when, if known; a photo taken from a safe distance may help identify the plant.
- Keep other people and pets away from the plant or any collected material.
Poison Control describes nervous-system effects including tremors, paralysis and breathing difficulty; severe cases can progress quickly. This guidance concerns people. USDA ARS also reports livestock-specific poisoning amounts and outcomes, but those figures are not human dose thresholds and should not be used to estimate an individual animal’s risk. Contact a veterinarian promptly if an animal may have eaten the plant.
How should poison hemlock be handled or removed?
Poison Control’s general yard-removal advice is to wear gloves and pull up the entire plant, roots included; it notes that a local agriculture office may help. Gloves are a precaution, not proof that handling is safe. Avoid touching your face, keep children away, and check local weed-management rules and recommended disposal methods before removal. For construction or property work, mark an uncertain plant and arrange identification or removal through an appropriate local professional rather than treating resemblance as confirmation.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Did poison hemlock really kill Socrates?
The traditional account attributes the execution of Socrates in 399 BCE to poison hemlock. The National Park Service identifies him as the best-known example of the ancient Greek use of the plant to execute prisoners. A 2024 article in Clinical Toxicology, by Anthony D. Dayan, revisits apparent mismatches between Plato’s account and expected poisoning symptoms. Dayan argues that translation discrepancies explain many of them and that the death can be treated as a limited case report of poison-hemlock poisoning. That is a scholarly historical interpretation, not a case confirmed by direct toxicological evidence.
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Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →Sources: National Park Service poison-hemlock profile; USDA Agricultural Research Service: Poison Hemlock; Poison Control: Poison hemlock; Dayan, “Socrates’ death—an expert toxicological review,” PubMed record.
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