Centaurea

Annual or perennial herbs, usually cano-tomentose. Leaves alternate, sometimes radical, entire or sometimes toothed or pinnatisect. Capitula usually disciform or 'radiate' (not true ray florets, radiant), solitary or corymbose, rarely in elongated clusters. Involucre ovoid or globose; bracts generally with fimbriate-ciliate or lacerate, variously shaped appendages. Receptacle nearly flat, often fleshy, densely setose. Florets with outer row of florets neuter, inner bisexual; corolla purple, blue, yellow or white, tube slender below, dilated above, deeply 5-lobed, papillose or hairy; neuter florets sometimes larger. Anthers with bases sagittate, adjacent lobes connate and drawn out into long or short, entire or lacerate tail; filaments papillose or hairy. Style abruptly thickened below branches and there furnished with ring of hairs; branches erect, connate, shortly bifid, lanceolate or linear, obtuse. Cypselas obovoid-oblong or obconical, somewhat compressed, glabrous or sparsely pilose; attachment scar lateral and oblique. Pappus generally double, outer row of scabrid, barbellate or plumose bristles or subulate scales, inner row or entire pappus rarely 0. x = 9 (7, 8, 10, 11) (aneuploids, B-chromosomes, polyploidy).