Spotted & Diffuse Knapweed
Centaurea biebersteinii, Centaurea diffusa
Description
State designated noxious weed. Height to 4 ft.; rosette first year. Spotted—pink to purple finely dissected compound daisy flowers with black fringe; June to September. Diffuse – finely dissected compound white flowers; can be pink to purple; June to September. Leaves are small, elliptical, yellow to brown bracts surround the flowers.
Habitat
Occurs in rangeland, meadows, roadsides, open and sandy soils.
Location in Nebraska
Fairly widespread in Nebraska, particularly in the northern counties.
Pathway of Introduction and Spread
Came from Eurasia in contaminated alfalfa and ship ballast; Spreads by seeds through water or animal movement.
Impacts
Allelopathic chemicals affect other plants. Establishes readily on disturbed ground, decreases forage production for livestock.
Dr. Sylvan Ramsey Kaufman and Wallace Kaufman. “Invasive Plants” 2007.
K. George Beck and James Sebastian, Colorado State University, Bugwood.org
Richard Old, XID Services, Inc., Bugwood.org