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.

mature giant hogweed plants
Numerous white flowers grow in umbrella-shaped clusters up to 2 feet across. Flowers mid-June to late July.

leaves of giant hogweed
Leaves are unevenly lobed and up to 5 feet wide. Plants can reach a height of 10 to 15 feet when in flower.

stem of giant hogweed
Hollow stems are 2 to 4 inches in diameter and have dark reddish-purple blotches.

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[Photos: Maine Department of Agriculture, Conservation and Forestry]