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. 2016^Footnote 1).

Worldwide: Native to the Caucasus region of Asia (Azerbaijan, Georgia, Russia) and cultivated in eastern Europe and Korea (USDA-ARS 2016^Footnote 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 2016^Footnote 3).

General Information

Hogweed has been cultivated as an ornamental, for fodder, and for honey production (CABI 2016^Footnote 3). Seed dispersal can occur by collection of dried fruiting heads for decoration (Kabuce and Priede 2010^Footnote 4), or by movement on agricultural and forestry vehicles (CABI 2016^Footnote 3).

Seeds are efficiently spread over long distances by water, following streams or floods (Kabuce and Priede 2010^Footnote 4). An average plant can produce approximately 9000 seeds (CABI 2016^Footnote 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 2010^Footnote 4).

Photos

Similar species