In order to limit the risk of extinction of the most endangered species, the establishment of protected areas is one of the means of action for biodiversity conservation policies. These protected areas make it possible, on the one hand, to remove natural habitats home to these endangered species from the various pressures leading to land take, and on the other hand to implement precautionary management measures, the role of which is to contribute to maintaining natural habitats and wild species at a favourable conservation status. The objective of this indicator is to assess the inclusion of endangered florist species through policies for the creation of protected areas. The species considered threatened are Critical Endangered Species (CR) and Endangered Species (EN) from the Ile-de-France Regional Red List of Plant Species. The locations of endangered species have been geographically crossed with the protection zones in order to determine: — the proportion of CR and EN species which are not protected by regulation and in essence, which are protected only in principle, only by regulation, or both; — the proportion of CR and EN species stations, which are not protected by regulation and in substance, which are protected only in real terms, only by way of regulation, or both. A mapping of CR and EN non-protected, protected and/or inherently protected stations was produced as a decision aid in the development of new protection zones. CR species are less well taken into account than EN species. The protection effort through the creation of new areas or the redefinition of existing perimeters should therefore in the future focus primarily on CR species on the Red List, with a clear priority on species not yet included in a protected area.