Updated list of non-native ornamental plants in Romania.
The first list of non-native ornamental plants (nNOP) reported as escaped, naturalised or invasive in Romania was published 15 years ago. Since then, new additions to the non-native ornamental flora of Romania have been reported, while others plants have changed their status. As ornamental horticulture is one of the most important pathways for non-native plant introduction worldwide, we evaluated nNOP at the national level and updated the previous list in order to contribute to the development of tools for preventing, detecting, monitoring and managing the spread of nNOP. The updated list includes 264 taxa. Most of these are casual (199 taxa), 37 taxa are naturalised, and 28 taxa are invasive. In addition, the following characteristics were analysed: family, native range, life form, abundance in the country reported as number of localities and temporal trends. Non-native ornamental flora of Romania is dominated by American and Asian taxa, phanerophytes, hemicryptophytes and therophytes. The most widespread species is Robinia pseudoacacia, used not only for ornamental purposes, but also for its economic value. Many taxa (108 taxa) occur only in two to ten localities. 78 nNOP have been reported in the last 20 years. Six taxa are species of European Union concern (Ailanthus altissima, Asclepias syriaca, Cabomba caroliniana, Humulopsis scandens, Impatiens glandulifera, Myriophyllum aquaticum) and require special measures to control and mitigate their populations.