Conyza bonariensis, (L.) Cronq.

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1976, Flora Europaea. Volume 4. Plantaginaceae to Compositae (and Rubiaceae), Cambridge University Press : 120

2. C. bonariensis (L.) Cronq. , loc. cit. (1943)

(C. ambigua DC. , Erigeron bonariensis L. , E. crispus Pourret ).

Like 1 but up to 250 cm, usually more densely hairy; inflorescence sometimes with elongate branches overtopping the main axis; capitula often lem or more wide; involucre 4-6mm, hirsute throughout, rarely glabrous or nearly so ( var. leiotheca (Blake) Cuatrec. ); female florets 50-120 or more; ligules up to 0-5 mm, shorter than the style and usually also than the pappus. 2я = 36, 54. Cultivated ground and waste places. Naturalized in the Mediter­ ranean region and S. W. Europe. [Al Az BI Co Cr Ga Gr Hs It Ju Lu Sa Si Tu.] (Tropical America.)

In Europe two variants are often recognized, one with a pyramidal inflorescence, dirty white to reddish-brown pappus and greyish-green involucral bracts, often with reddish apex, and the other with a more or less cylindrical inflorescence, yellowish pappus and greenish-brown involucral bracts. The latter is known as C. floribunda Kunth in Humb., Bonpl. & Kunth, Nov. Gen. Sp. 4: 73 (1820) (C. naudinii Bonnet). Other variants have sometimes been interpreted as 1 x 2 and have been called C. x flahaultiana (Thell.) Sennen, Bol. Soc. Aragon. Ci. Nat. 15: 98 (1916). Study of native populations does not support the taxonomic recognition of these variants, even at subspecific rank, though they often form colonies of distinctive facies in Europe.