Species › Plants › Poison Hemlock

Poison Hemlock

Conium maculatum

CommonPlant
Illustration of Poison Hemlock (Conium maculatum)
Safety note: Highly toxic — all parts contain coniine, which can cause paralysis and death. Do not ingest or handle with bare hands.

Poison Hemlock is a non-native biennial in the carrot family introduced from Europe, now widespread in disturbed areas, roadsides, and stream banks across North America. It is recognized by purple-spotted hollow stems and fine, fern-like leaves. The plant that killed Socrates in ancient Greece, it remains one of North America's most dangerous introduced plants.

Habitat
Roadsides, disturbed areas, stream banks, and waste places
Diet
Flowers support many generalist insects; otherwise has limited wildlife value
How common
Common

Best time to see a Poison Hemlock

The best time to see a Poison Hemlock is April–June, when about 69% of U.S. sightings happen, based on 38,927 research-grade iNaturalist observations.

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Not certain it is a Poison Hemlock? What plant is this? walks through what to check first and the lookalikes that catch people out.

Often confused with

Queen Anne's Lace - see how to tell them apartCow Parsnip - see how to tell them apart

Recent Poison Hemlock sightings near you

Live, research-grade observations from iNaturalist. Allow location to center the map on you.

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