From a Release
This non-native, invasive plant is spreading very quickly along rivers and streams. Giant Hogweed is a serious health hazard for humans. Its clear, watery sap contains toxins that can cause severe inflammation of the skin.
You can get severe burns if you get the sap on your skin and the skin is then exposed to sunlight, as UV radiation activates compounds in the sap.
“If you find what you think is Giant Hogweed, do not go near or touch the plant under any circumstances,” advised Brandon Williamson, Land Management Technician for the Upper Thames River Conservation Authority. “The issue is people getting sap on themselves by touching or breaking the stems, stepping on the plant, or even brushing against the leaves.”
Symptoms occur within 48 hours and consist of painful, burning blisters that can cause severe irritation, dermatitis, and develop into purplish or blackened scars. Depending on individual sensitivity, effects can last for months and skin can remain sensitive to UV light for years. Eye contact with the sap has been reported to cause temporary or permanent blindness.
The Giant Hogweed outbreak began several years ago along the North Thames River and has been moving rapidly down the river valley.
“Hogweed grows along streams, ditches and roadsides, and is invading old fields and even woods,” said Williamson. “If you’re out for a hike or canoeing on the river, you need to watch out for it.”?
Description of Giant Hogweed
Giant Hogweed can be much taller than a grown person, reaching up to 5 m (16 ft.) in height. It has large, flat-topped to slightly dome-shaped white flowers and seed heads and bumpy or bristly stems. The huge leaves are 1-1.5 m (3-5 ft) wide, and shaped like an exaggerated maple leaf.