The alien vascular flora of Stromboli and Vulcano (Aeolian Islands, Italy)

The updated censuses of the alien flora of the islands of Stromboli and Vulcano, Aeolian Islands in the Central Tyrrhenian Sea, are presented here. They currently consist of 40 and 57 specific and subspecific taxa respectively. As many as 16 and 18 taxa respectively are new in comparison with the last censuses in 2016. Mesembryanthemum x vascosilvae, commonly cultivated in both islands, is reported for the first time as naturalized alien to Italy. Passiflora incarnata from Stromboli and Pelargonium graveolens from Vulcano are reported for the first time as casual aliens to Sicily. The evolution over time of these florulas, as inferred from the main floristic works published on these islands, is commented on. Biology, ecology and possible causes of settlement of these plants are discussed briefly.