Giant hogweed (Heracleum mantegazzianum) is a towering invasive plant from the Caucasus whose clear, watery sap can cause severe skin burns and even blindness. It is a genuine public-health concern where it grows, so learning to recognize it — from a safe distance — matters. Never touch a plant you suspect is giant hogweed.
How to Identify Giant Hogweed
- Enormous size — mature plants tower 8 to 14 feet tall
- Huge, flat-topped white flower clusters (umbels) up to 2.5 feet across, like a giant Queen Anne's lace
- Thick green stems with dark reddish-purple blotches and coarse white hairs
- Massive, deeply cut, jagged leaves up to 5 feet wide
Why It Is Dangerous
Giant hogweed sap contains compounds that make skin extremely sensitive to sunlight (phytophotodermatitis). Contact followed by sun exposure can cause painful blistering burns within a day or two, long-lasting scars and dark marks, and serious eye injury if sap reaches the eyes.
What to Do If You Touch It
- Wash the area immediately with soap and water and keep it out of sunlight for at least 48 hours
- Flush eyes with water and wear sunglasses if sap contacts them, and seek medical care
- See a doctor for any burns or blistering
- Do not try to cut or remove giant hogweed yourself — report it to your state agriculture or environmental agency for professional removal
Look-alikes like cow parsnip, angelica, and Queen Anne's lace cause needless panic — and true giant hogweed is sometimes missed. From a safe distance, photograph the plant and let Spotter help identify it before you go anywhere near it.
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