The technical advises given for the management of perennial pastures are generally based on the botanical description of the plant community. The notion of functional plant types makes it possible to propose a more generic typological method, that is less time-consuming and necessitates less botanical knowledge. This typology of perennial forage grasses was built up using the values of 6 functional characteristics that discriminate among the agricultural qualities of the species. Thanks to these characteristics (for the leaves: dry matter content, specific foliar area, length of life duration,resistance to breakage; for the whole plants: flowering date, maximum height), 38 species of grasses could be distributed among 6 functional groups with different potential use values. These values regard the plants’ growth strategies (capture or conservation of the resources), their phenology (early or late), their aptitudes for accumulating bio-mass, their frequency of use and their feeding values.