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Weed Seed: Heracleum mantegazzianum (Giant hogweed)



Common Name

Giant hogweed


Primary Noxious, Class 2 in the Canadian Weed Seeds Order, 2016 under the Seeds Act.


Canadian: Occurs in BC, ON, QC, NB, NL, NS (Page et al. 2006Footnote 1).

Worldwide: Native to the Caucasus region of Asia (Georgia, Russia) and introduced in Europe, North America, Australia and New Zealand (USDA-ARS 2016Footnote 2).

Duration of Life Cycle

Monocarpic perennial (dies after flowering)

Seed or fruit type

Schizocarp, divided into 2 mericarps

Identification features



Surface Texture


Other Features

Habitat and Crop Association

Fields, gardens, pastures, grasslands, open forests, forest edges, forested floodplains, shorelines, ditches, landfills, gravel bars, roadsides and urban parks (Darbyshire 2003Footnote 3, Page et al. 2006Footnote 1). Not a common agricultural weed (Page et al. 2006Footnote 1).

General Information

Giant hogweed was planted in European botanical gardens of the early 19th century as an ornamental and was first recorded in Canada in 1949 in Ontario (Page et al. 2006Footnote 1). It favours regions with cool, moist climates and soils with high organic matter (Page et al. 2006Footnote 1, CABI 2016Footnote 4).

Similar Species

Cow parsnip (Heracleum sphondylium subsp. montanum)


Giant hogweed (Heracleum mantegazzianum) mericarps
Giant hogweed (Heracleum mantegazzianum) mericarp, outer side
Giant hogweed (Heracleum mantegazzianum) mericarp, inner side
Giant hogweed (Heracleum mantegazzianum) teeth along the edge of mericarp, especially near the top of the fruit

Similar species

Similar species: Cow parsnip (Heracleum sphondylium subsp. montanum) mericarps
Similar species: Cow parsnip (Heracleum sphondylium subsp. montanum) mericarp, outer side
Similar species: Cow parsnip (Heracleum sphondylium subsp. montanum) mericarp, inner side
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