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Species
Information
- giant
hogweed
- Heracleum
mantegazzianum (Sommier & Levier)
- USDA
Symbol: HEMA17
- Oregon
Noxious Weed Designation: A
- Pictures
ALERT: PLEASE CALL 1-866-INVADER IF YOU SUSPECT YOU HAVE FOUND THIS SPECIES
Identification: Perennial; flowers May-July. Grows 10-15 ft tall. Stalk and flower head develop after 2-4 years, then plant dies back. Stalks stout (2 to 4 inches in diameter), hollow, have reddish-purple blotches and pustules with a single erect hair in the center. Flower head is a large umbrella-like inflorescence up to 2 1/2 feet in diameter. Leaves 3 to 5 feet wide, compound and deeply incised. This plant closely resembles native cow parsnip which rarely exceeds 6 feet with a flower head 8-12 inches wide.
Impacts: This plant is a public health hazard. Do not expose bare human skin to the plant or breathe the smoke from fires if it is being burned. The plant exudes a clear watery sap which sensitizes the skin to ultraviolet radiation. Humans often develop severe burns to the affected areas resulting in blistering and painful dermatitis. Blisters can later develop into purplish or blackened scars. Giant hogweed has been introduced to Europe, Canada, and the United States as an ornamental. Because of its invasive nature it soon becomes a pest within the garden and readily escapes. It has naturalized in many of the places where it was introduced, and is one of the most invasive weeds in Europe.
Biological
Controls: Biological control agents are not used on "A" listed weeds in Oregon. This weed is being managed for eradication or containment.
Oregon
Maps of Giant Hogweed Distribution
Links:
USDA
Plants Database information on giant hogweed
GRIN
Database information on giant hogweed
Oregon Department
of Agriculture information on giant hogweed
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