Giant Hogweed—Heracleum mantegassianum
An invasive perennial and a public health hazard: Contact with sap followed by sun exposure can cause painful blistering. Grows in moist soil, especially in ditches and ravines in both sun and shade.
Numerous white flowers grow in umbrella-shaped clusters up to 2 feet across. Flowers mid-June to late July.
Leaves are unevenly lobed and up to 5 feet wide. Plants can reach a height of 10 to 15 feet when in flower.
Hollow stems are 2 to 4 inches in diameter and have dark reddish-purple blotches.
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Identification and Control Information
- Giant Hogweed—Maine Department of Agriculture, Conservation and Industry, Division of Animal and Plant Health
- Giant Hogweed Look-a-Likes—Maine Department of Agriculture, Conservation and Industry, Division of Animal and Plant Health
- A Homeowner's Guide To Managing Giant Hogweed brochure [PDF]—Maine Department of Agriculture, Conservation and Industry, Division of Animal and Plant Health
- Fact Sheet: Giant Hogweed (PDF) —United States Department of Agriculture
- Fact Sheet with Identification and Control Methods (includes lots of pictures) (PDF) —The Ohio State University Extension
- Fact Sheet with Identification Tips and Control Methods (PDF) —King County Washington
- Species Identification Card: Giant Hogweed (PDF) —Gulf of Maine Research Institute, Vital Signs Program
More Information
- Invasive Alien Plant Species of Virginia: What are Invasive Alien Plant Species and why are they a problem?—Virginia Department of Conservation & Recreation
- Alien Plant Invaders of Natural Areas brochure (PDF) —Plant Conservation Alliance
- What the heck is an invasive plant brochure (PDF) —Plant Conservation Alliance
[Photos: Maine Department of Agriculture, Conservation and Forestry]