Bidens frondosa, L.

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 : 140

6. B. frondosa L. , Sp. PI. 832 (1753)

( B. melanocarpa Wieg. ).

Almost glabrous annual 10-100 cm. Leaves petiolate, pinnate, with l (-2) pairs of petiolate pinnae and a larger, terminal pinna; pinnae oblong-lanceolate to ovate, acute or acuminate, coarsely serrate. Capitula 10-20 mm in diameter, erect, wider than long; outer involucral bracts 5-8, herbaceous, sometimes leaf-like, somewhat villous near the base, the inner ovate-oblong, blackish, with a scarious margin. Receptacular scales as long as the achenes, oblong, scarious, with dark lines. Achenes 5-8 mm, cuneiform, rugose, with erect hairs on the face and margins; bristles 2, erect. 2« = 48. Widely naturalized in W., S. & C.

Europe. [Au Be Br Cz Ga Ge He Ho Hs Hu It Ju Lu Po Rs (W) Si.] (America.)