Notulae to the Italian alien vascular flora: 20

In this contribution, new data concerning the distribution of vascular flora alien to Italy are presented. It includes new records, exclusions, and status changes from casual to naturalized or invasive for Italy or for Italian administrative regions for taxa in the genera Bidens , Ceratochloa , Chamaeiris , Cylindropuntia , Cyperus , Euphorbia , Freesia , Glinus , Hydrocotyle , Lagunaria , Megathyrsus , Myriophyllum , Opuntia , Schinus , Sparaxis , Sporobolus , Talinum , and Tradescantia . Nomenclatural and distribution updates, published elsewhere, and corrections are provided as Suppl. material.