Centaurea diffusa Lam.
Initial growth is in the form of a rosette.
Lower leaves are early deciduous. Cauline leaves are alternate, smaller, and pinnatifid, while the upper reduced leaves are entire. Achenes are 2-3 mm long, light brown to black, with the pappus generally absent or consisting of only a fringe of bristles less than 1 mm long. The bracts of spotted knapweed have dark tips with no spine. Russian knapweed has rounded bracts with pointed papery tips.