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Weed Seed: Rhaponticum repens (Russian knapweed)



Common Name

Russian knapweed


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


Canadian: Occurs in AB, BC, MB, ON, SK (Brouillet et al. 2016Footnote 1).

Worldwide: Native to eastern Europe and temperate Asia and introduced in North America, Argentina, Australia, and beyond its native range in Europe (USDA-ARS 2016Footnote 2).

Duration of life cycle


Seed or fruit type


Identification features



Surface Texture


Other Features

Habitat and Crop Association

Cultivated fields, old fields, pastures, rangelands, ditches, roadsides, railway lines and disturbed areas (Watson 1980Footnote 3, Darbyshire 2003Footnote 4). Reported as a weed of alfalfa (Watson 1980Footnote 3).

General Information

Russian knapweed was introduced into Canada in the early 1900s as a contaminant in alfalfa seed (Watson 1980Footnote 3). This species is found on a variety of soil types, and has been noted to invade areas where it was not directly introduced (Watson 1980Footnote 3).

Russian knapweed seed can persist in the soil for up to 75 years, and the plants also readily reproduce through stem buds borne on the roots (Watson 1980Footnote 3). A dense patch of plants can spread up to 12 square metres in 2 years (Watson 1980Footnote 3). Leaves and stems are also reported to be toxic to horses (Watson 1980Footnote 3).

Similar species

Gumweed (Grindelia squarrosa)


Russian knapweed (Rhaponticum repens) achenes
Russian knapweed (Rhaponticum repens) achene
Russian knapweed (Rhaponticum repens) achene, side view
Russian knapweed (Rhaponticum repens) flower head

Similar species

Similar species: Gumweed (Grindelia squarrosa) achenes
Similar species: Gumweed (Grindelia squarrosa) achene
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