The Vascular Flora of Sirente-Velino Regional Park (Abruzzo, Central Italy)

We present the first vascular flora of Sirente-Velino Regional Park, a protected area located in central Apennine (Abruzzo, Central Italy), covering 550 km². The floristic inventory was compiled based on extensive field surveys conducted from 1990 to 2025. Thanks to specific funding secured for the final three years (2023-2025), field trips became systematic, aimed at covering the entire territory of the park, including its diverse habitats across different seasons. Furthermore, an analysis of the relevant literature was performed, alongside a comprehensive review of herbarium specimens housed at APP, FI, NAP, and RO. The park's flora comprises 2066 taxa (1370 species and 696 subspecies, including 11 hybrids), belonging to 117 families and 671 genera, with 122 classified as alien. Notably, 169 taxa are endemic to Italy. Our study reports 234 taxa for the first time within the park, while 52 remained unconfirmed in recent times and 22 are of doubtful occurrence. Five taxa are newly recorded for the Abruzzo region: Alchemilla alpinula, A. obtusa, A. vulgaris, Hyacinthoides non-scripta, and Salsola tragus. Additionally, the revision of APP herbarium specimens led to the exclusion of Euphorbia tommasiniana from the regional flora, reassigning the material to the alien E. saratoi. The species richness of the native flora exceeds expectations by 50.8%, a finding likely driven by the area's significant geographical, geological, and microclimatic diversity, which results in high environmental heterogeneity. Conversely, alien taxa are 5.6% lower than expected, probably due to the high ecological integrity of the park, a predominantly mountainous territory with low population density and minimal anthropogenic disturbance. Representing 20.6% of the entire Italian flora, the Sirente-Velino Regional Park stands out as one of Europe's protected areas with the greatest diversity of vascular plants.