Cyperus schweinitzii (Cyperaceae): a new naturalized alien in Italy

Cyperus schweinitzii Torr. (Cyperaceae), a xenophyte native to North America, is reported for the first time in Italy. A considerable population was found on a railway yard in Stradella (Lombardy), where the species is naturalized. Until now, C. schweinitzii had been recorded outside of its native range only on the French railway network. Diagnostic characters are presented and an original drawing is provided. Additionally, its possible means of introduction and its invasive status are discussed.