Ammannia auriculata, Willd.

Tutin, T. G., Heywood, V. H., Burges, N. A., Moore, D. M., Valentine, D. H., Walters, S. M. & Webb, D. A., 1981, Flora Europaea. Volume 2. Rosaceae to Umbelliferae, Cambridge University Press : 302

1. A. auriculata Willd. , Hort. Berol. l: t. 7 (1803).

Glabrous; stem up to 1 m, erect, subtetragonal, simple or with ascending branches. Leaves up to 90 x 8 mm, usually longer than the internodes, linear-oblong, acute to acuminate, cordate-auriculate at the base. Cymes 3- to 15-flowered, with peduncles and at least some of the pedicels clearly visible. Hypanthium 2-3 mm, campanulate; sepals reduced to very short teeth; epicalyxsegments even smaller or absent. Petals 2-5 mm, fugacious; stamens 4, rarely more. Style 2-3 mm; capsule globose, slightly exceeding hypanthium. Naturalized in rice-fields. N.W. Italy (around Novara and Vercelli). [It.] (Widespread in tropical and warm-temperate regions.)

The European plant is referable to var. arenaria (Kunth) Koehne , and is probably of American origin.