The introduction and acclimatization of exotic plant species in the South-East of France, in particular since the second half of the nineteenth century, have contributed to the domestication of wild species used in ornamental horticulture, perfume industry and landscape. A few species have naturalized, some have become invasive and are impacting the highly endemic indigenous flora. Early detection of naturalizing species and evaluation of biological invasion risk are useful for control or eradication operations. The question arises for woody plant species introduced since 1973 in a forest arboretum of the Esterel Mountains. Out of 400 species planted initially, 13 are naturalizing, among which several species of Hakea genus (Proteaceae) native of Australia. This study aims to assemble useful data for the invasion risk evaluation. These data include reproduction traits, seed bank, dispersion system and introduction history. Risk analysis confirmed that several species can become a threat to the environment if they naturalize outside the arboretum. Two of them (Hakea salicifolia (Vent.) B.L. Burtt and Hakea sericea Schrad. & J.C. Wendl.) already have an invasive status in other Mediterranean countries. Studies lead to the production of a technical itinerary and to the local operators' awareness to organize control. This method could be applied to other arboretums, especially those situated in the Mediterranean region.