A comparative analysis was undertaken to conduct a micromorphological study of Pistacia atlantica leaves by comparing different populations grown under different climatic conditions. Leaf epidermis of eight wild populations was investigated under scanning electron microscope. Micromorphological characteristics (epidermis ornament, stomata type, waxes as well as trichomes) of the adaxial and abaxial leaf surfaces were examined. The epidermis ornament varied among populations and leaf surface, the abaxial leaf surface is reticulate with a striate surface. Messaad site shows a smooth uneven surface. The adaxial leaf surface is smooth but several ornamentations can be seen. The leaflet is amphistomatic; the stomata appeared to be slightly sunken. A variety of stomatal types were recorded; actinocytic and anomocytic types are the most frequent. The indumentum consisted of glandular and nonglandular trichomes. Unicellular glandular trichomes are recorded for P. atlantica leaves in this study. Their density is higher in Oued safene site, located at the highest altitude in comparison with the other populations. The wax occurred in all the sites and its pattern varied according to the populations studied, particularly between Berriane and Messaad. The morphological variability exhibited by the eight populations of P. atlantica may be interpreted as relevant to the ecological plasticity and the physiological mechanisms involved are discussed in this report. Microsc. Res. Tech. 70:837-846, 2007. V

To study the morphological variability within and among Pistacia atlantica Desf. populations, a comparative analysis was undertaken in eight wild populations grown under different climatic conditions in Algeria. This study addresses the morpho-biometrical aspect of the leaves and the fruits, as well as the micromorphological aspect of leaves. ANOVA as well as mean comparison of the morphological traits revealed a significant diversity within and among the populations. Furthermore, in the multivariate analysis, the populations were separated into four different groups through the discriminating variables: leaf and leaflet dimensions, number of pairs of leaflets, leaf wings, leaf smell and colour, terminal leaflet size and apex, and finally fruit colour and shape. These results showed the originality of the Algerian populations as compared with those commonly described for this species in the literature, in particular by the occurrence of wax on the leaves. The morphological variability exhibited by the Algerian populations of P. atlantica may be interpreted as relevant to the ecological plasticity and the physiological mechanisms discussed in this article.