Photo Credit: Nicole Kimmel, Alberta Agriculture & Forestry
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Common Name: Spotted Knapweed Scientific Name: Centaurea stoebe Habitat: roadsides, disturbed areas, gravel pits, grassland, grassland dry Provincial Designation: Prohibited Noxious Prohibited Noxious weeds are plant species that are designated as "prohibited noxious" in the Alberta weed regulation. Prohibited noxious weeds must be destroyed, meaning all growing parts need to be killed or the plant's reproductive mechanisms need to be rendered non-viable. |
Origin
Spotted knapweed is native to Eastern Europe. It was introduced to North America as a contaminant in alfalfa seeds in the 1890s.
Legislated Because
Infestations of spotted knapweed form monocultures that displace forage for wildlife and livestock. It prefers to invade disturbed areas in particular. Its roots release chemicals into the soil that inhibit the growth of other plants.
Description
The flowers of spotted knapweed are 6-15 cm wide and the bracts have hair-like margins. These hairs are shorter than the triangular centre of the bract. The bracts also have distinctive dark vertical stripes.
The stem leaves are deeply lobed and each lobe is narrow.
The leaves and the stem are covered in hairs and are grey-green in colour. Each plant has several erect stems that grow 40-150 cm tall.
Learn more about this species:
See Fact Sheets - Alberta Invasive Species Council
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Spotted Knapweed -
Spotted Knapweed -
Spotted Knapweed -
Spotted Knapweed
