May 17, 2024 - Health

Keep an eye out for poison hemlock

Side by side images of poison hemlock plants.

Poison hemlock can be harmful if ingested. Photos: Courtesy of Joe Boggs/OSU Extension

The plant that may have killed Socrates could also be growing in your backyard.

The big picture: Poison hemlock has spread widely in central Ohio over the past few years. But experts say it remains a largely underappreciated hazard in the area.

Why it matters: It's one of the deadliest plants in North America, so you should probably at least know how to recognize it.

State of play: Poison hemlock is a highly invasive ornamental that contains a potent poison that, yes, was said to have been used by the Athenians to execute Socrates.

  • And Michael Hogan, an agriculture extension agent at OSU, tells Axios he's been seeing it just about everywhere lately.

What they're saying: "It's just kind of exponentially increased," Hogan says, recounting sightings in alleyways, in unmaintained areas along roadways and even sprouting out of sidewalk cracks.

Threat level: The good news is that poisonings are relatively rare. Unlike poison ivy or wild parsnip, you need to ingest part of the plant or its sap rather than touch it for it to harm you.

Zoom in: Aerosolized sap was enough to hospitalize a Cincinnati-area man for more than 100 days in 2021 after he spent an afternoon using an electric chainsaw cutting down what was, to him, an unknown nuisance plant.

How it works: Poison hemlock spends its first year as a low-growing plant. In subsequent years it can grow as tall as 6 to 10 feet, has purplish spots on its stems and produces flowers often mistaken for Queen Anne's Lace.

  • Hogan says your best bet is to hit any poison hemlock you identify on your property with a spray herbicide like Roundup as early as possible in the growing season.

Go deeper: See OSU Extension's website for more details on identifying and eradicating the plant.


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