Phylogenetic analysis have been conducted on representatives of Poaceae groups temptatively placed within subtribes Cynosurinae, Dactylinae, Loliinae, Parapholiinae, Phalaridinae, Poinae, and Sesleriinae. Sequences from the nuclear ITS region and from the chloroplast trnL-F region have been analyzed either separately or combinedly to obtain a reconstruction of the evolutionary relationships between these predominantly Western Mediterranean lineages. The structures shown on the resulting topologies differentiate several suprageneric groups that could be reaccomodated within Poeae s. lat. Some of the best supported clades represent the links of: 1) Festuca s.s. + Vulpia + Wangenheimia + Ctenopsis+ Psilurus; 2) Schedonorus + Lolium; 3) Dactylis + Lamarckia+ Parapholis + Monerma + Catapodium + Sphenopus + Cynosurus. Leucopoa, and Drymanthele + Scariosa + Subbulbosae could be resolved either separated or basal to Schedonorus + Lolium. Sesleria and Poa are respectively sister lineages to the other studied taxa. Conflicts between the nuclear and the chloroplast trees are likely due to past intergroup hybridization events. Evaluation of changes of structural characters on the molecular trees confirms their phylogenetic value at some hierarchical levels.

Key words: combined phylogenies, ITS, Poeae, reclassification of groups, trnL-F