The forests of the Tolfa-Ceriti mountains (Latium, central Italy) were investigated through a phytosociological approach. 249 relevés were performed and treated with multivariate analysis. 13 woodland communities were identified, of which 7 belong to Quercetalia pubescenti-petraeae, 1 to Fagetalia sylvaticae, 1 to Populetalia and 4 to Quercetalia ilicis. The thermophilous Turkey oak-forests occurring on the trachytic hills of the Ceriti Mountains and on the flysch substrates of the Tolfa Mountains were included in Rubio peregrinae-Quercetum cerridis ass. nova. Quercus cerris and Fraxinus angustifolia subsp. oxycarpa woodland communities of the footslopes have been ascribed to Fraxino oxycarpae-Quercetum cerridis, while the widespread mesophilus Turkey oak forests have been ascribed to Melico-Quercetum cerridis. Cephalantero longifoliae-Quercetum cerridis has been restricted to acid and oligotrophic soils. Quercus petraea woodlands, occurring on trachytic substrates have been described as a new association named Carici olbiensis-Quercetum petraeae ass. nova. All these mixed oak woods have been included in the alliance Crataego laevigatae-Quercion cerridis Arrigoni 1997. The nomenclatural problems concerning the prior name Teucrio siculi-Quercion cerridis Ubaldi 1988 are also discussed. The beech forests of the higher altitudes have been included in Fraxino orni-Fagetum sylvaticae, while the Alnus glutinosa ravine woodlands have been described as belonging to the new association Polysticho setiferi-Alnetum glutinosae. Secondary communities of Acer monspessulanum and Acer campestre developed on flysch substrates, and of Erica arborea and Arbutus unedo (Erico-Arbutetum unedonis) developed on trachytic substrates, have also been identified. Finally two types of Quercus ilex wood have been identified: Cyclamino repandi-Quercetum ilicis, on sandstones, and the new association Arbuto unedonis-Quercetum ilicis ass. nova on volcanic soils. This latter community can be considered as a coenological and geographical vicariant in central Italy of the sicilian Erico-Quercetum ilicis.
