First report of Houttuynia cordata in Italy
Houttuynia cordata (Saururaceae) is a perennial herb native to temperate and tropical Asia. In the native range, it is utilised as a medicinal plant, as a vegetable, and as a garden ornamental. It has been introduced into the EPPO region as a garden ornamental. Globally, H. cordata is naturalised in South America, and invasive in New Zealand, Madagascar, the USA and Costa Rica. In the EPPO region, it is recorded as a casual species in Austria, Belgium, the Czech Republic and the United Kingdom. In Hungary it is reported as established. In 2019, H. cordata was found along the banks of the river Stella in the municipality of Palazzolo dello Stella (Northeast Italy). Here it was growing in a disturbed riverine woodland. Over 2 years, a significant expansion of the initial population was observed. In July 2019, the population occupied less than 1 m2 with less than 10 shoots, while in June 2020, the population was formed by 3–4 stands, occupying at least 50 m2 with more than 70 shoots. These observations suggest an ongoing establishment and spread with a high invasive potential. Although it there is no evidence to how the species arrived in this location, it is considered that it spread from gardens through flooding events.
Sources
Liccari F, Boscutti F, Sigura M, Tordoni E, Carpanelli A, Valecic M, Bacaro G (2021) First report of naturalization of Houttuynia cordata Thunb. 1783 (Saururaceae) in Italy. Rendiconti Lincei. Scienze Fisiche e Naturali. https://doi.org/10.1007/s12210-021-00986-2