The genetic diversity within and between three natural populations of Argania spinosa in south west Morocco was investigated by using nine morphological characters of simple and grouped leaves for three consecutive seasons. Relative contribution of seasonal variations and seasonal variations x locality interaction on the phenotypic variance is low (0% to 17.1%) for all characters of simple and grouped leaves. Relative contribution related to genotype x environment interaction (season x tree / locality) on the phenotypic variance is greater (17% to 40.5%) for all traits except for leaf length, midrib length and dry matter content in simple leaves (0% to 14.9%). Argan tree shows a high degree of genetic diversity especially within populations than between populations. Leaf length, midrib length, leaf width, leaf area and stomata number are the most discriminating characters, being responsible for 54.6% of the total variation, but differentiation between the three populations was not established. This substantial genetic variation for morphological characters provides a database for genetic improvement of agromorphological characters given that the argan tree is source of food for a large number of herds especially in times of drought in arid environments.