Silphium perfoliatum, 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 : 142

1. S. perfoliatum L. , Syst. Nat. ed. 10, 2: 1232 (1759).

Stems up to 250 cm, 4-angled, glabrous. Leaves triangular-ovate, coarsely toothed, acute, the lower up to 30 cm, long-petiolate, the upper abruptly contracted into a winged petiole; wings of pairs of petioles connate to form a cup round the stem. Capitula pedunculate, in a corymbose inflorescence. Involucre 15-25 x 12-25 mm; bracts ovate, glabrous. Cultivated for ornament’, occurs as a casual and locally naturalized, on river-banks and in damp meadows in C. Europe. [Cz Ge He.] (North America.)