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June 25, 2018 -- Experts in Virginia are warning people to be on the lookout for giant hogweed, a dangerous plant that might make poison ivy seem tame.

Giant hogweed is an invasive species that can grow up to 14 feet tall, with beautiful blooms similar to those of Queen Anne’s lace. Although nice to look at, the plant produces a toxic sap that can cause serious blisters, third-degree burns, and permanent blindness.

Despite its dangers, giant hogweed was introduced to the U.K. and U.S. from Central Asia in the early 1900s as ornamental plants for gardens. Today, the plant has been reported in Connecticut, Illinois, Maine, Massachusetts, Michigan, New York, Pennsylvania, Oregon, Virginia, and Washington. The U.S. government considers it a noxious weed, one that is harmful to the environment, and it cannot be freely bought and sold.

Virginia is the newest addition to the list of states that house the weed, which is considerably farther south than where it’s been known to dwell. Researchers at the Massey Herbarium at Virginia Tech recently identified 30 of the plants growing in Clarke County.

“The Clarke County population is not spreading,” the researchers write on Facebook, “and you’re very unlikely to see giant hogweed in Virginia.”

The Facebook post from the researchers asked locals to report any sightings of the plant to a local extension agent.

Giant hogweed can be hard to remove completely. To be sure it doesn’t grow back, you have to remove the entire root and avoid spreading the seeds. Don’t try to use a weed-whacker on them; the sap on the stems could splatter into your eyes, which can cause permanent blindness. Instead, conservation experts recommend calling professionals who can properly remove and destroy the plant.

Even though experts don’t think it’s moving any time soon, knowing how to identify the plant could prevent a particularly painful reaction.

Giant hogweed is a close relative of cow parsnip, a native plant found in nearly every U.S. state, including Virginia. Both weeds cause similar skin reactions, but the giant hogweed’s effect is much worse. Here’s how to identify it:

  • Large, incised leaves up to 5 feet
  • White, umbrella-shaped flower clusters up to 2.5 feet wide
  • Green stem with purple splotches and coarse white hairs
  • Sap covers the whole plant, particularly the leaves and stems.

The sap contains a compound that causes phytophotodermatitis, a condition that causes severe inflammation when skin is exposed to sunlight.

If the sap gets on your skin:

  • Immediately wash with soap and cold water
  • Avoid sunlight
  • If the sap gets in your eyes, rinse them with cold water immediately and wear sunglasses.

According to the New York Department of Environmental Conservation, the reaction can start as soon as 15 minutes after reaching the skin, and it reaches peak sensitivity between 30 minutes and 2 hours after contact.

Inflammation causes painful, colored blisters to form within 48 hours. Places where the sap touched the skin could have long-term sensitivity to light and scarring.

Some steroid creams can reduce the severity and pain. Contact your doctor for more information.

Show Sources

USDA National Invasive Species Information Center: “Plants: Giant Hogweed.”

USDA National Invasive Species Information Center: “Heracleum mantegazzianum Sommier & Levier.”

CBS News: “Giant hogweed, plant that causes blindness and third-degree burns, discovered in Virginia.”

Facebook: VT Massey Herbarium, June 12, 2018.

Facebook: VT Massey Herbarium, June 20, 2018.

National Invasive Species Working Group: “Giant Hogweed National Fact Sheet.”

Popular Science: “This giant demon plant gives you burns if you touch it, and it’s spreading.”

New York State Department of Environmental Conservation: “Health Hazards & Safety Instructions for Giant Hogweed).”

New York State Department of Environmental Conservation: “Giant Hogweed Identification.”

USDA Index of Species Information: “Species: Heracleum maximum.”


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