Abstract:
Four species of Centaurea are commonly found in central and
eastern Oregon, including spotted knapweed (Centaurea
maculosa), diffuse knapweed (Centaurea diffusa), Russian
knapweed (Centaurea repens), and yellow starthistle
(Centaurea solstitialis). These four species are a serious problem
throughout Oregon and the Pacific Northwest. Stands of knapweed can choke out natural vegetation by competing for water and nutrients.
