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Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

1120 SW 5th Avenue, Room 1000, Portland, OR 97204

More Contact Info

Are there any lookalikes?

Yes. Poison hemlock (Conium maculatum) is a weedy non-native that is frequently confused for giant hogweed. Poison hemlock has small seedheads and carrot-like leaves, resembling a very large Queen Anne’s lace. While not being managed by ED/RR, it is a species around which caution should be used.

Poison hemlock (Conium maculatum) is a weedy non-native that is frequently confused for giant hogweed. Poison hemlock has small seedheads and carrot-like leaves, resembling a very large Queen Anne’s lace. While not being managed by ED/RR, it is a species around which caution should be used.

Consultation with City of Portland or Oregon Department of Agriculture staff is strongly recommended before management of suspected hogweed begins. Call the Oregon Invasives Species Hotline, 1-866-INVADER (1-866-468-2337), or Mitch Bixby with the Environmental Services Early Detection, Rapid Response Program at 503-823-2989.

Cow parsnip (Heracleum lanatum, see photos below) is a native cousin with a sap that can have similar effects, though usually much less potent than hogweed. Cow parsnip tends to be shorter, with seedheads all about the same size, and relatively flatter leaves, but these differences can be very subtle.

cow parsnip

Cow Parsnip (up to 2 feet across)

hogweed leaves

giant hogweed (up to 4 feet across)

cow parsnip

cow parsnip ( 6-10 in flat cluster)

hogweed seed heads

giant hogweed (seedheads up to 2 ft in diameter)