Posted on 06.29.21 by Harney SWCD

By Tyler Goss

Diffuse Knapweed comes to us from Asia Minor and southern Russia.  It can be found throughout Oregon and Idaho as a biennial.

During the plant’s first year, a deep tap root with broad leaves is produced.  In the following year, it will grow a single stem that will branch with a flower bulb at the end.  The plant will typically grow one to two feet tall.  The bulb will blossom into a purple head, a half inch in diameter with spearhead-shaped seeds.

Diffuse Knapweed is nearly drought tolerant, establishing feverishly in overgrazed upland range sites.  It is also common on roadsides.   Biological controls are effective—high intensity grazing is recommended.