Asteraceae (Sunflower family)
Class B Noxious Weed
Control or Containment Required
Diffuse knapweed, a Class B noxious weed in Franklin County, arrived in the U.S. as a contaminant in alfalfa from the Caspian Sea region of Turkistan. This invader competes with desirable plants for nutrients, light and moisture.
A tap-rooted biennial or short-lived perennial, it has an upright stem that produces several spreading branches that upon maturity have a rounded form. Flowers are typically white but are sometimes pink or lavender. Flower bracts are tan colored, fringed with slender spines.
Reproduction occurs primarily by wind-dispersed seeds. A single plant can produce as many as 18,000 seeds.
Download our printable PDF with more information about diffuse knapweed and best management practices for controlling it.
Diffuse knapweed begins as a rosette.
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