Centaurea diffusa Lam.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Diffusely branched annual or biennial 1–6 dm; herbage sparsely scabrous-puberulent under the thin and deciduous arachnoid tomentum; lvs small, ± pinnatifid, the lower ones deciduous, the reduced ones of the infl mostly entire; heads numerous, narrow; invol 8–10 mm, the middle and outer bracts coarsely pectinate or weakly spinose-ciliate, and tipped with a definite slender spine 1.5–4 mm; fls few, white, seldom yellowish or pinkish or red, the marginal ones not enlarged; pappus none; 2n=18. A weed in waste places, native to se. Europe, and now found here and there in our range. July–Sept.