Centaurea macrocephala, also known as Lemon Fluff, Golden Thistle, Bighead Knapweed, and Armenian Basket Flower, is now on the prohibited list in Alberta. Therefore, if you have this plant in your garden, remove it immediately. Do not share it or let it go to seed.
This perennial has large showy, single yellow flowers and large, broad, rough, hairy, lance-shaped leaves with pointed tips. It grows up to 1.5 metres tall. The roots are woody. Centaurea macrocephala is a prolific invader that spreads by seed. The striking flowers make it easy to spot and identify when blooming.
Alternatives to Centaurea Macrocephala
Alternatives include the Centaurea dealbata, a pink/purple blooming knapweed also called Persian Thistle or Persian Cornflower, and any one of several varieties of yellow blooming Heliopsis or false sunflower. Artichoke has a similar flower type, although the colour is blue instead of yellow.
Other noxious weeds in Alberta: