The phenology of leaf abscission in different woody species with deciduous, marce- scent and evergreen habits was studied over a complete annual cycle. Statistical treat- ment of the data permit the characterization of each species as a function of abscis- sion time and of the length of the abscission period (estimation of the greater smaller degree of gradualness of leaf fall). Abscission time seems to be related moisture stress; the sooner the water deficit becomes apparent, the earlier the fall. The length of the abscission period does not depend on the deciduous, marce- scent or evergreen nature of the species; neither is it apparently related to the phylo- genetic affinity of the different species. The latter finding means that a prolonged abscission period could indeed be an adaptive trait of the species better suited more infertile soils.