Ambrosia trifida, 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 : 143

5. A. trifida L. , Sp. Pl. 987 (1753).

Annual up to 200 cm. Stems patent-hirsute or hispid above, glabrous below. Leaves petiolate, opposite, scabrid, broadly elliptical to ovate-orbicular, palmately 3- to 5-lobed, sometimes entire. Male involucre c. 1 mm, cup-shaped; bracts tuberculate; male flowers 10-15; corolla present. Female involucre 6-10 mm in fruit, many-ribbed, each rib ending in a short spine. 2л = 24. Cultivated ground and waste places. Naturalized in a number of European countries. [Cz Ga Ge It Rs (B, W, E).] (North America.)