Are All Knapweed Invasive?

Meadow knapweed flower Page 2 Knapweeds are invasive plants that can overtake grasslands thereby reducing pasture productivity, hay quality and outcompeting native prairie plants. Infestations increase soil erosion and water runoff as well as reduce wildlife habitat quality in natural areas.

What problems does knapweed cause?

Spotted knapweed has many negative impacts. For example, it releases a chemical that hinders native plants' root growth and displaces vegetation. Also, infestations can decrease food quantities for wildlife and livestock. As well, large infestations can increase erosion and runoff.

How can you tell if a spot is knapweed?

Flowers are pink to light purple (rarely cream colored) and the petals are surrounded by stiff, black-tipped bracts, giving the flower head a spotted appearance (Figures 3 and 4). The black tipped bracts found below the flower petals are the key feature to distinguish spotted knapweed from other knapweed species.