A dataset on invasive alien plants of European Union concern.

We present PREVALIEN, a dataset created under the project Prevention and Early Detection of the Invasive Alien Plants of European Union Concern in the Italian Protected Areas, an innovative tool supporting prevention and early detection of Invasive Alien Plants. Developed on PostgreSQL, it integrates ecological and spatial data from authoritative European and global sources. This dataset covers 41 vascular plant and algal species, with detailed information on taxonomy, traits, introduction pathways, impacts, and management strategies. Presence and absence records for Italians' protected areas were obtained from the Italian Institute for Environmental Protection and Research databases and included only if collected within National Park boundaries. Data underwent expert verification, including cross-checking with risk assessments and consultation with park authorities. Structured into 34 relational tables, PREVALIEN supports multi-scale ecological analysis and the development of spatially explicit risk models. As an open-access resource, it fills critical data gaps, enhances national IAS monitoring, and provides a foundation for evidence-based policies and actions against biological invasions, strengthening protection of Europe's most vulnerable and biodiversity-rich landscapes.