Giant Hogweed

Heracleum mantegazzianum

Giant Hogweed1
Giant Hogweed2
Giant Hogweed3
Giant Hogweed4

Giant Hogweed - A perennial, or sometimes biennial, plant capable of growing 15-20 feet tall. Stout dark reddish-purple splotched stems and leaf stalks.

Leaves: Leaves can grow up to 5 feet wide, and they are deeply cut/lobed and sharply toothed edges.

Flowers: Flowers bloom from June-August. Flower clusters can grow 2.5 feet wide and are umbrella shaped with many small white flowers.

Habitat: Can grow in a variety of habitats, but primarily found along roadsides, rights-of-way, vacant lots, streams, and rivers.

Weed Classification: A

Why is it a Noxious Weed?

Due to the plant's height, it forms dense canopies that outcompete native species. Plants exude a clear, watery sap that makes skin sensitive to UV radiation. This sap causes blistering and dermatitis, and the scars can last up to 6 years, with the UV sensitivity lasting longer.

Giant hogweed can be dangerous and has been found within Lewis County. It can be mistaken for other (smaller and native) plants, so let us know if you think you've found some!

Control Recommendations:

WA State Noxious Weed Board

PNW Pest Management Handbook

UC Davis Weed Report