IntroduzioneIl massiccio di origine vulcanica del Monte Arcuentu, situato nell'Arburese, è un area per la quale non esistono sino ad oggi analisi di tipo botanico se si eccettuano la segnalazione floristica di Picci (Picci, 1969) Most of the recored taxa were belonging to Asteraceae (71), followed by Fabaceae (52) and Poaceae (51). Most frequent genera are: Trifolium (11), Euphorbia (9), Allium, Geranium, Juncus, Medicago, Ophrys, Orobanche (7). The biological spectrum highlights the remarkable Mediterranean connotation of the studied district, being the therophytes (40.8%), followed by hemicriptophytes (27.0%) and geophytes (14.7%) being the most frequent growth forms. Indeed, the chorologic spectrum is dominated by the Mediterranean chorotype (48.4%), whose main partitions are: steno-Mediterranean (22.8%), endemic (9.7%) and W-Medit. (9.3%). Taxa with a broader distribution range, but centred in the Mediterranean basin, represent the 26.6%. The endemic taxa were 54 , among which Asteraceae (8) and Fabaceae (5) were the most represented families. The chorologic spectrum of the endemic units is dominated by Sardo-Corsican taxa (20), followed by Italo-Tyrrhenian ones (14). The analysis of rarity, according to the categories of Rabinowitz, highlighted the fact that the largest group (231) consists of WBL (i.e. species diffused over the territory, with a wide ecology and a large local population, in some places dominant), while the smallest one (5) is formed by the NBL (i.e. species with a limited spread over the territory, a wide ecology and a large local population, at times dominant). The taxa protected by international regulations are all the recorded orchids (19) and Cyclamen repandum subsp. repandum, included in the attached II of CITES, Brassica insularis in the Berne Convention, 2 in the Habitat Directive (Brassica insularis and Ruscus aculeatus), plus 3 (Soleirolia soleirolii, Hyoseris taurina and Genista morisii) cited in the IUCN-red lists.