Invasive Plant

Giant Hogweed

Heracleum mantegazzianum
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Warning

Giant hogweed plants produce a highly toxic sap that can cause burns, blisters and scarring if you touch it. WorkSafeBC has issued a Toxic Plant Warning for Giant hogweed requiring workers to wear heavy, water-resistant gloves and water-resistant coveralls that completely cover skin while handling the plants. Eye protection is also recommended.

About This Species

Giant hogweed is an invasive plant listed as noxious throughout the province of BC according to the BC Weed Control Act Regulation. Currently it’s found in the Lower Mainland, Fraser Valley, Gulf Islands, and central to southern Vancouver Island.

How to Identify

Giant hogweed is easily differentiated from other species due to its unusually large size. Multiple umbrella-shaped clusters of white to light pink flowers can be up to 80 cm across on a single stem. Stems are hairy, green with purple blotches, 5-10 cm in diameter and up to 5 m tall. Its leaves are dark green, coarsely toothed, deeply incised leaves. Leaves are alternate. The lower leaves are up to 3 m long and 1.7 m wide and coarsely toothed. Upper leaves on the flowering stem become smaller. The upper leaf surface is smooth, but the underside is covered in bristles.  Green oval fruits are about 4 mm to 10 mm in diameter and 6 mm to 8 mm wide. Seeds form in June and July turning dry and brown when ripe.

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INVASIVE SPECIES INFORMATION

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A few non-invasive alternatives to plant instead of Giant Hogweed include:

  • Blue elderberry (Sambucus cerulea)
  • Ligularia (Ligularia dentata)
  • Rodgersia (Rodgersia spp.)
  • Shieldleaf rodgersia (Astilboides tabularis)
  • Wild celery (Angelica spp.)

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