Weed Seed: Heracleum sosnowskyi (Hogweed)
Primary Noxious, Class 2 in the Canadian Weed Seeds Order, 2016 under the Seeds Act.
Canadian: Absent from Canada (Brouillet et al. 2016Footnote 1).
Worldwide: Native to the Caucasus region of Asia (Azerbaijan, Georgia, Russia) and cultivated in eastern Europe and Korea (USDA-ARS 2016Footnote 2).
Duration of life cycle
Monocarpic perennial (dies after flowering)
Seed or fruit type
Schizocarp, divided into 2 mericarps
- Mericarp length: 10.0 - 16.0 mm
- Mericarp width: 5.0 - 9.0 mm
- Mericarp is long oval, flattened
- Dull, hairs on dorsal side of mericarp
- Light yellow mericarp with brown oil ducts
- Teeth along the edge, especially near the top of the mericarp.
- The oil ducts extend ¾ down the mericarp and have enlarged ends.
Habitat and Crop Association
Fields, old gardens, farmyards, pastures, meadows, grasslands, bushlands, abandoned orchards, forest edges, parks, river valleys, roadsides, railway lines, and disturbed areas (CABI 2016Footnote 3).
Hogweed has been cultivated as an ornamental, for fodder, and for honey production (CABI 2016Footnote 3). Seed dispersal can occur by collection of dried fruiting heads for decoration (Kabuce and Priede 2010Footnote 4), or by movement on agricultural and forestry vehicles (CABI 2016Footnote 3).
Seeds are efficiently spread over long distances by water, following streams or floods (Kabuce and Priede 2010Footnote 4). An average plant can produce approximately 9000 seeds (CABI 2016Footnote 3).
Giant hogweed (Heracleum mantegazzianum)
- The mericarps of giant hogweed are a similar oval shape, flattened, enlarged oil ducts and marginal teeth to hogweed.
- Giant hogweed mericarps tend to be more narrow, have few or no hairs, are more yellow-coloured and the oil ducts are red compared to hogweed's brown oil ducts. Hogweed is also more shade tolerant than giant hogweed (Kabuce and Priede 2010Footnote 4).
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