Distribution of the invasive giant hogweed Heracleum mantegazzianum in Italy

Heracleum mantegazzianum, commonly known as giant hogweed, is a highly invasive plant species in Europe, included in the list of invasive alien species subject to regulation in the European Union. Native to the Caucasus Mountains in Southwest Asia, it has established itself in several temperate regions around the world, raising concerns due to its ecological impacts and risks to human health. In Italy, it was introduced in the late 19th century and has since escaped from cultivation and spread, but it has also disappeared from numerous sites, either because it failed to establish or was successfully managed. Consequently, information on its presence is inconsistent, and a comprehensive overview of its distribution is lacking. This study compiles and updates records from multiple sources—including field surveys, herbarium collections, and literature—to provide an overview of its distribution in the country. The results highlight that, despite recent control measures, H. mantegazzianum remains widespread in northern Italy, particularly across the Alpine region. This makes it a priority for monitoring and management strategies, especially as climate change may facilitate its range expansion to higher elevations, increasing the risk of invasion in mountain ecosystems rich in endemic species, which are both vulnerable and of high conservation value.