In the course of 4 to 6 years demographic studies were made of several coastal populations of Anthyllis vulneraria L. var. langei Jalas and of an inland population of the var. vulneraria. Fluctuations in the population density, in the biomass and in the rate of flowering were recorded, and in addition the relation between life span and flower production was investigated. Coastal populations appear to exhibit a far greater fluctuation in density, annual biomass production and rate of flowering than the inland population studied. These different degrees of fluctuation are associated with differences in the environment. In the interior, fewer flowers are produced per plant and the plants more often flower only once, whilst more plants start flowering at a later age than is the case in coastal populations. The differences in the pattern of flowering are most probably correlated with the denser stands of vegetation at the site in the interior where the mutual competition among the plants is stronger. The total life-span of the plants appears to be about the same near the coast and in the interior.