Cabomba caroliniana Gray (Cabombaceae) invades major waterways in Belgium

Recently, unattached viable stem fragments of the invasive macrophyte Cabomba caroliniana Gray were found at several locations in two canals in northern Belgium. A subsequent survey of the canal Zuid-Willemsvaart revealed one site with rooted plants and the presence of floating stem fragments along the entire length of the canal (25 km). These findings indicate that C. caroliniana is already well established in the Zuid-Willemsvaart and probably considerably more widespread than previous records from isolated lentic water bodies indicate. We have summarised the new records and discuss the potential spread and risks associated with further establishment and spread of C. caroliniana in Belgium.