Land Plants - invasive

Giant Hogweed (Heracleum mantegazzianum) on May 4, 2026

Submitter has sample

Description of specimen

Two plants found side by side. No flowers yet. 2-5 ft currently. Stalks are very green (lime green) and maroon color (specs and dense) like with large white prickly hairs.

Commentary

None

Resources

There are many plants that look similar to giant hogweed, including our native cow parsnip. Giant hogweed is truly giant, often 7' to 14' tall, with leaves that can be up to 5' wide. There are some great photos comparing giant hogweed to similar species on the New York Dept of Environmental Conservation website.

Location

I am a manager of a large facilities ONPRC OHSU. Our campus is locked down, and visits have to be scheduled. I and my landscape team manage 200+ acres on our campus. This plant was found on our site off of Colony Road. It is on a partial access gravel road. My expert Landscape crew identified this plant as "Hogweed." My cell phone app identified this plant as Cow Parsnip. We were going to treat the plant with chemical to eliminate it. After further research I have been advised to reach out. It is currently alive but not flowering. 503-346-5206 and bonillag@ohsu.edu

Expert Reviewer

Avatar of Reviewer

Coleman Hepner
Tualatin SWCD

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