Russian Knapweed (Centaurea repens L.)

Russian knapweed is perennial, forming dense colonies by adventitious shoots from widely spreading black roots. Stems are erect, openly branched, 18 to 36 inches tall. Lower leaves are deeply lobed, 2 to 4 inches long; upper leaves entire or serrate, narrow to a sessile base. Cone-shaped flowering heads are 1/4 ro ½ inch in diameter, solitary at the tip of leafy branchlets. Flowers are pink to lavender. Many pearly involucral bracts form with rounded or acute papery margins.

Russian knapweed is a native of Eurasia, probably introduced in North America about 1898. It is now widely established in the western U.S. This species forms colonies in cultivated fields, orchards, pastures and roadsides. Russian knapweed plants spread by black, deep growing roots which penetrate to a depth of over 8 feet. Flowering occurs from June to September.

If you would like more information, email MWCA at acamm@montana.edu with your questions. A weed control expert will be happy to answer your questions.