Cullahill Mountain is listed as Special Area of Conservation under the European Union Habitats Directive. The site has a large population of Green-winged Orchid which is a rare species that is legally protected under the Irish governments Flora Protection Order (1987). The orchid flora of the grassland is notably rich, with Twayblade, Frog Orchid, Bee Orchid, Early-purple Orchid and Green-winged Orchid. The west side of site extends downslope to an Ash and Hazel woodland.