First report of naturalization of Houttuynia cordata Thunb. 1783 (Saururaceae) in Italy

The Chameleon plant ( Houttuynia cordata Thunb.—Saururaceae) was introduced across all continents from Asia for ornamental and medicinal purposes at least two centuries ago. H. cordata is deemed a strong invader thanks to its great ability for rapid vegetative propagation by means of rhizomes and stolons (and their fragments) coupled with a high resistance to herbicides. Moreover, it has been suggested that H. cordata has the potential to displace native plants in wet forests and, in general, in wetland ecosystems. In New Zealand and North America, this species has been included in the black list of invasive alien species and it is included in a special control program for monitoring and eradication. In this study, we record the first established naturalized population of Houttuynia cordata in Italy. It was found in July 2019 in a riverine Salix woodland. After revisiting the location, a significant expansion of the initial population was observed in June 2020, suggesting its naturalization with great invasive potential. Criteria and procedures defined by the regional intervention priorities on alien species were applied to further monitor and eradicate the species, as an example of good practice for the management of alien species.