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Photo Credit:  Alexander Mrkvicka, Botanik im Bild, retrieved from http://flora.nhm-wien.ac.at, modified from the original

Common Name: Tyrol Knapweed

Scientific Name: Centaurea nigrescens

Habitat: roadsides, disturbed areas, grassland, forests - open areas

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

Tyrol knapweed is a perennial native to western Asia and south-western Europe.

Legislated Because

Tyrol knapweed can invade open forests, grasslands, and prairies. It can out-compete native vegetation, reduce biodiversity and forage species.

Description

The flowers of Tyrol knapweed are 20-30 mm wide and have peripheral petals that are distinctively larger than its inner petals. The bracts have hair-like margins. The 'hairs' are shorter than the triangular centre of the bract allowing the lower green part of the bracts to be visible.

Most leaves are lance-shaped or elliptic. A few leaves on each plant might have one or two lobes. The leaves and the stem have stiff hairs.

Tyrol knapweed grows up to 150 cm tall.

Learn more about this species:

See Fact Sheets - Alberta Invasive Species Council

For More Information

Weed Management

Telephone

In Edmonton: 311

Outside Edmonton: 780-442-5311

Email invasiveweeds@edmonton.ca

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