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Photo credit: Cindy Roche, Retrieved from Bugwood.org (Image Number: 1350057), used under CC BY 3.0 US, modified from the original

Common Name: Brown Knapweed

Scientific Name: Centaurea jacea

Habitat: grassland; dry or wet, forests - open areas - but prefers moister areas than other Knapweed species

Provincial Designation: Prohibited Noxious

Prohibited Noxious weeds are plant species designated in the Alberta Weed Control Act. Prohibited noxious weeds must be destroyed when found, meaning all growing parts need to be killed or the plant's reproductive mechanisms need to be rendered non-viable.

Origin

Brown knapweed is native to Europe and was probably introduced to North America as an ornamental species.

Legislated Because

Brown knapweed can invade open forests, grasslands, and prairies. It can out-compete native vegetation, reducing biodiversity and available forage species.

Description

Brown knapweed flowers are 15-25 cm wide. Bracts usually have a distinctive papery margin and are light brown called bracts, which are modified leaves underneath the flower petals. The leaves are lance-shaped or shallowly lobed and become progressively smaller up the stem. The fruits usually don't have a plume or bristles.

In the first year of growth, brown knapweed only has leaves on the ground (in a rosette).  It grows a stalk and blooms in the second and subsequent years. Brown knapweed grows up to 150 cm tall.  The stems are rigid and may have purple stripes.

It can hybridize with black knapweed, which creates plants that look slightly different from either parent species.

Learn more about this species:

See Fact Sheet - 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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