Rotala ramosior (L.) Koehne, Fl. Bras. (Martius), 13 (2): 194. 1877.

( Lythraceae)

Naturalized neophyte new to the flora of the province of Alessandria (Piemonte) (Celesti Grapow et al., 2009a).

ITALY. Piemonte. Prov. Alessandria: Villanova Monferrato, rice fields, 12.09.2014, F. Verloove 11079 (BR) .

Rotala ramosior originally is an American species but it occurs in the Old World as a weed of rice fields, for instance in Italy and the Philippines (Cook, 1979). In Italy it was first discovered in Piemonte in 1972 (Cook, 1973), subsequently also in Lombardia (Banfi & Galasso, 2010). In the past decades it has repeatedly been confirmed from Piemonte (e.g. Soldano, 1977; Abbà, 1980; Varalda et al., 1984; Desfayes, 2005) but it seemed to be confined to the province of Vercelli, from where it was originally reported by Cook (1973). In September 2014 it was found, apparently for the first time, in the province of Alessandria. It was found growing in quantity, with Ammannia coccinea Rottb. and other weeds, in a rice field near Villanova Monferrato.