Weed Seed: Heracleum sosnowskyi (Hogweed)

Family

Apiaceae

Common Name

Hogweed

Regulation

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

Distribution

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

Identification features

Size

  • Mericarp length: 10.0 - 16.0 mm
  • Mericarp width: 5.0 - 9.0 mm

Shape

  • Mericarp is long oval, flattened

Surface Texture

  • Dull, hairs on dorsal side of mericarp

Colour

  • Light yellow mericarp with brown oil ducts

Other Features

  • 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).

General Information

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).

Similar species

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).

Photos

Figure 1 - Hogweed (Heracleum sosnowskyi) mericarps
Hogweed (Heracleum sosnowskyi) mericarps
Figure 2 - Hogweed (Heracleum sosnowskyi) mericarp, outer side
Hogweed (Heracleum sosnowskyi) mericarp, outer side
Figure 3 - Hogweed (Heracleum sosnowskyi) mericarp, inner side
Hogweed (Heracleum sosnowskyi) mericarp, inner side
Figure 4 - Hogweed (Heracleum sosnowskyi) mericarps, inner side (R) and outer side (L)
Hogweed (Heracleum sosnowskyi) mericarps, inner side (R) and outer side (L)
Figure 5 - Hogweed (Heracleum sosnowskyi) mericarp, brown oil duct in centre
Hogweed (Heracleum sosnowskyi) mericarp, brown oil duct in centre

Similar species

Figure 6 - Similar species: Giant hogweed (Heracleum mantegazzianum) mericarps
Similar species: Giant hogweed (Heracleum mantegazzianum) mericarps
Figure 7 - Similar species: Giant hogweed (Heracleum mantegazzianum) mericarp, outer side
Similar species: Giant hogweed (Heracleum mantegazzianum) mericarp, outer side
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