The flow cytometry technique has been applied in order to check the ploidy level of seven provenances of local alfalfa (Medicago sativa L.) Gabsi, to estimate the genome (pg DNA) size of these alfalfa lines and to verify whether any genetic differences existed between these provenances belonging to the same population. Flow cytometry technique enabled us to show that all sources are tetraploid but also showed genetic variability that can be explained by the effect of microclimate, even if it is obvious that all these sources belong to a same unique population.