First record of two invasive aquatic weeds Ludwigia repens (Onagraceae) and Myriophyllum aquaticum (Haloragaceae) in Poland

The aquarium trade has contributed to the introduction of many invasive alien plant species that threaten the structure and functioning of aquatic ecosystems around the world. In this study, I present the first Polish record of Ludwigia repens (Onagraceae) and Myriophyllum aquaticum (Haloragaceae), two invasive alien aquatic plants cultivated in aquaria. The plants were found on the shores and in the waters of an artificial pond in Kraków, southern Poland, in 2024. The location and abundance of both species are documented, and their introduction pathway and naturalization potential are discussed. Moreover, since M. aquaticum belongs to the invasive alien species of European Union concern and requires rapid eradication, its occurrence was reported to the Kraków City Office, following Polish law.