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Giant Hogweed

(Heracleum Mantegazzianum)

This page was reviewed or revised on Monday, September 27, 2010 10:51 AM

What is giant hogweed?

Giant hogweed is a hardy perennial plant that comes from Asia and was introduced to North America as an ornamental garden plant.

The plant can grow 4.5 - 6.0 metres (15-20 feet) tall. Its stem is hollow with dark reddish-purple splotches and coarse white hair. The leaves can grow up to 1.5 metres (5 feet) wide and have hairs on the underside. It produces flat, oval shaped fruit and in the summer, small white flowers.   Photo credit: City of Coquitlam

How can it affect my health?

A clear, watery sap found in the stem and plant hairs can cause a reaction that makes the skin sensitive to sunlight.

Photo courtesy of USDA APHIS PPQ Archive, USDA APHIS PPQ, Bugwood.org

Reactions can happen up to 48 hours after contact. You can get painful blisters and burns.Blisters can lead to purple and black scars that may last for long periods. Contact with the eyes can cause temporary and sometimes permanent blindness.

What should I do if I contact hogweed?

• Wash affected areas immediately
• Keep the affected area out of the sun
• Seek medical advice

What should I do if I find a giant hogweed?

Because of the possible health effects caused by the Giant Hogweed, remove it from your property as soon as possible. When removing it, avoid getting sap on your skin. Wear protective clothing, including gloves, long sleeves, pants, and eye protection.

For instructions to remove this plant contact:

• County of Lambton
  Building Services:
  519 845-5420
  
• City of Sarnia
  Community Services:
  519 332-0330 ext. 213

For more information contact:

• Community Health Services Department
  519 383-8331, toll free 1-800-667-1839
  www.lambtonhealth.on.ca
  
• or visit:
  http://www.omafra.gov.on.ca
  http://www.ontarioweeds.com