Giant Hogweed

Giant Hogweed

Scientific name: Heracleum mantegazzianum

Common names: Giant hogweed

Description: A plant from the carrot family, giant hogweed can grow up to 15 feet high when flowering. The white flower clusters are umbrella-shaped and sit on top of hollow, purple to red blotched stems. Giant hogweed is most often found in wet soils and can grow in both full shade and full sun. Similar in appearance to the native cow parsnip (Heracleum lanatum), giant hogweed is most often distinguishable by its larger size.

Impact: The large, aggressive character of giant hogweed gives it a competitive advantage over many native species. When it dominates hillsides and stream sides it can lead to increased risk of erosion due to its shallow roots and its propensity to die back during the rainy Pacific Northwest winters. The sap of giant hogweed is a serious phototoxin causing the skin to become hypersensitive to sunlight. From kingcounty.gov: “If sap gets on the skin, immediately wash with soap and water; keep exposed skin out of the sun and treat as you would a surface burn.” If you come across giant hogweed in the county please contact our office at 503-325-4571.

Source: KingCounty.gov

For more information, please visit the Noxious Weed resources at KingCounty.gov: http://www.kingcounty.gov/services/environment/animals-and-plants/noxious-weeds/weed-identification/giant-hogweed.aspx