Skip to main content

I Spot Knapweed!

Posted on 08.02.21 by Harney SWCD

by Tyler Goss

Spotted Knapweed is a biennial or short-lived perennial plant of the Asteraceae family native to Eurasia. It looks similar to the Scotch thistle plant, but grows thinner, has smaller flower heads, and branches out much more. The flower head is round shaped with pink colored flower. It is much taller than other knapweeds. The plant itself is a blue green color.

Spotted Knapweed (also known as “pioneer plant”) can be found in every Oregon and Idaho county, often in disturbed soils common to ephemeral and dry stream beds.  It can easily be controlled with common herbicides such as 2,4-d. Mechanical controls should start before flowering.

A purple thistle flower with buds on a green stem against a blurred natural background.
Purple wildflowers by a wooden post, with gravel and grasses around.
A map showing the distribution of Centaurea stoebe ssp. micranthos across the United States, marked in green.