Centaurea L.

Herbs, usually rigid. Leaves alternate, entire, toothed or pinnatifid. Heads usually heterogamous, corymbose or panicled, solitary, ovoid or globose. Florets purple, violet, blue, white or yellow. Outer florets 1-seriate, neuter. Disc florets female, fertile; tube slender; limb straight or oblique, 5-fid to middle or lower. Involucral bracts many-seriate, imbricate, appressed, margins scarious or coriaceous or ending in a simple or palmately divided spine or pectinate appendage. Receptacle flat, densely bristly. Anther bases sagittate; auricles connate; tails long or short, entire or lacerate. Style arms with a thickened hairy basal ring. Achenes oblong or obovoid, compressed or obtusely 4-angled. Pappus many-seriate, various or absent.

Europe, N. Africa, N. China, America, Australia; ca 600 species, 6 in India.

Notes. Mostly cultivated as an ornamental.

Literature. WAGENITZ, G. (1955). Pollen morphologie and systematik in der Gattung Centaurea L. Flora 142: 213-279.

KEY TO THE SPECIES

1a. Branches white; outer involucral bracts ending in pectinate appendage

1. Centaurea bruguiseriana

b. Branches green; outer involucral bracts not ending in pectinate appendage

2

2a. Involucral bracts not spiny

3

b. Involucral bracts spiny

4

3a. involucral bracts cottony; pappus ca 4 mm long

3. Centaurea cyanus

b. Involucral bracts glabrous; pappus ca 7 mm long

4. Centaurea depressa

4a. Flowers yellow

6. Centaurea melitensis

b. Flowers usually purple

5

5a. Young leaves lanate; involucre 6-8 mm in diam.

2. Centaurea calcitrapa

b. Young leaves green, hispidulous; involucre 9-14 mm in diam.

5. Centaurea iberica

List of Lower Taxa