Invasive Plant Guide: Spotted Knapweed


Centaurea maculosa

Both Spotted knapweed & Meadow knapweed infestations occur in the Mid Klamath area.

Spotted Knapweed Flower

Identifying characteristics

  • Flower color: pinkish purple with fuzzy white center
  • Flowers: July to September
  • Plant height: 8 inches to 6 feet
  • Stems: One or more, branching
  • Basal leaves: feathery, lobed
  • Bracts: tipped with dark tinged
  • Growth habit: biennial or short-lived perennial with stout taproot
  • Similar to Meadow knapweed


From 400-4000' elevation, adaptable to a variety of habitats. Moist areas, dry roadsides, in the shade or sun.

Spotted knapweed has small, isolated occurrences along the Klamath River and upslope sites.  Most of these are in and around Orleans.

Spotted Knapweed Plant


Spotted and Diffuse Knapweed were first discovered by the USFS on the Salmon River in 1997, with concentrated populations in the Kelly Bar vicinity on the North Fork Salmon River. Both species are rated "Class A" species, which mandates eradication as described in county and state health codes. Local land managers promoted the status quo management approach, which was to apply several different herbicides for at least five years. In response, the local community launched one of the most effective noxious weed efforts known in the region, significantly reducing or eliminating knapweed plant concentrations in over 250 sites. This program was taken up by MKWC volunteers on the Klamath River in 2001.

More Info

California Department of Food & Agriculture