First record of the non-native flowering plant Dichondra argentea (Convolvulaceae) in southern Europe and Italy: floristic, distributive and ecological notes

The creeping perennial flowering plant Dichondra argentea (Convolvulaceae), generally cultivated as ornamental for its nice silvery falling foliage, is native to South-Central America and it was found along the riverbank of Tiber River in a ruderal site in the city of Rome (central Italy). This finding represents the first record of a spontaneous population of D. argentea in southern Europe and Italy. This population has been monitored for two consecutive springs (2019 and 2020) and in both surveys it turned out to be vital and capable to spontaneously produce flowers, fruits and seeds. The arrival of D. argentea in this site could be due to an accidental escape from a nearby plant nursery. The species seemed to adapt well to local environmental conditions, both tolerating the arid summers and surviving to submergence of the winter floods of the adjacent Tiber river. A contribution to the knowledge of D. argentea biology, distribution and ecology outside its native range was provided. In addition, its status of local invasiveness has been discussed, and D. argentea, at the moment, should be considered as casual, although according to our observations it might have the potential to naturalize as it occurred for the similar non-native congeneric D. micrantha.