Fifty-four natural populations of Medicago truncatula were evaluated for flowering time, and winter and spring growth at two different climatic locations (sub-humid and semi-arid), in Algeria. Differences among populations, previously grouped into distinct maturity classes, were assessed by ANOVA, while the relationship between population characteristics and altitude and annual rainfall of collection sites was investigated by simple correlation analysis. Early and mid-season populations with appreciable vegetative growth were individuated. Flowering time resulted correlated with both altitude and rainfall of collection sites in the sub-humid location and only with rainfall in the semi-arid one.