The wide diversity within the Medicago sativa complex is well known, but comparative data on different populations representing the sub-species sativa and falcata are lacking. Morphological and agronomic characters of 25 populations or varieties of lucerne belonging to the M sativa complex were studied at Lusignan (France) in 1993 and 1994. The landraces and varieties of the sub-species sativa were clearly different from the wild populations of the 2 sub-species sativa and falcata by their erect growth habit, their fast regrowth after cutting, the absence of rhizomatous plants, their tall height and their high forage yield. Within the cultivated populations, those originating from northern France had a higher winter resistance than the Mediterranean populations, and higher yields. The winter resistance trait and the variegated flowers of the French sativa landraces show that they have integrated some traits belonging to sub-species falcata. The group of wild populations contained diploid and tetraploid populations, and sativa or falcata populations. Among the characters analysed, only flower colour made the distinction possible between the wild sativa populations from Spain (Mielga) with purple flowers and the falcata populations with yellow flowers. This convergence of forms between the 2 sub-species could be a strategy of tolerance to animal feeding and to treading.