Giant hogweed (Heracleum mantegazzianum) is a member of the carrot family that can grow to be more than 14 feet tall. When combined with moisture and sunlight, a phototoxin in the plant's clear sap can cause severe skin and eye irritation, blistering, permanent scarring and even blindness, according to the New York State Department of Environmental Conservation. Those who come into contact with the sap can remain sensitive to sunlight for several years after the initial exposure.
On its website, the Department of Environmental Conservation did not mince words when it advised residents to be cautious around the species: "Do not touch this plant!"
Officials in Virginia are investigating reports of a recent sighting in Staunton, and they warned that the highly invasive species has the potential to become more widely established in the state.
Though the most recent warning about the plant came from Virginia, the species has been reported in Maine, New York, Massachusetts, Connecticut, Pennsylvania, North Carolina and parts of the Pacific Northwest.
The plant produces white flowers that form an umbrella-shaped canopy over its stems, which contain purple splotches and coarse, white hair-like structures. There are multiple lookalike plants, the most common being cow parsnip. Cow parsnip is smaller than giant hogweed and doesn't have the purple splotches, the DEC explained.
If you think you have come into contact with giant hogweed, wash the impacted area with soap and water and keep it out of direct sunlight for 48 hours. Various state government agencies also ask residents to report giant hogweed sightings and provide photographs of the plant and its location for further investigation.
Native to the Caucasus Mountains, giant hogweed was introduced to the United States in 1917. It made its way around the world with collectors working for botanical gardens, according to the Virginia Department of Conservation and Recreation. In addition to the threat it poses to humans, giant hogweed can block sunlight from ground-level plants beneath it, making it difficult for those plants to survive.