Meadow Knapweed

Meadow Knapweed Asteraceae (=Compositae), the aster family

Meadow KnapweedBACKGROUND: Meadow knapweed is native of Europe and can grow in many environmental conditions. Meadow knapweed is believed to be a fertile hybrid resulting from crossbreeding black knapweed (C. nigra) and brown knapweed (C. jacea).

DESCRIPTION: Meadow knapweed is a perennial plant up to 3 1/2 feet tall. Basal leaves are up to 4 inches long, slender, have a petiole, and may be entire, toothed, or lobed. Stem leaves usually don’t have a petiole and are much smaller. Stems are many branched and tipped by a solitary flower head up to 1 inch wide. Flowers are pink to reddish purple and are produced from midsummer the rough fall. Flower head bracts are 1/4 inch wide, and the tips range from a comblike fringe to a blunt ruffled edge. Bract tips range from tan to dark brown or, rarely, black. Seeds are brown to gray in color and are tipped by plumes that fall off at maturity.

Meadow KnapweedDISTRIBUTION: Meadow knapweed is found from British Columbia to northern California.

CONTROL: A biological control agent has provided fair results on meadow knapweed in Washington but is still under evaluation in Idaho. Herbicides are available for control.

Meadow Knapweed Distribution Map - Grey Area

 

© 1999 University of Idaho: Text and photographs for these pages from Idaho’s Noxious Weeds, by Robert H. Callihan and Timothy W. Miller (revised by Don W. Morishita and Larry W. Lass).

Please contact: Ag Publishing, University of Idaho, Moscow, Idaho 83844-2240; (208) 882-7982; cking@uidaho.edu; or visit the UI Extension/CALS Publications and Multimedia Catalog website at www.cals.uidaho.edu/edComm/catalog.asp, for more information about this or other publications.