Like other threatened species, detailed knowledge of the food habits of the Souss Valley Tortoises (Testudo graeca graeca) is important for its conservation and management. We determined the composition of the diet and its seasonal changes using fecal microhistological analysis in tortoises from an arid steppe-land of the central Jbilet Mountains, west-central Morocco, between spring 2011 and winter 2012. Tortoises were exclusively herbivorous with a specialist trend selecting rare, very rare, or some abundant plant species. Diets differed among seasons as indicated by Margalef's Richness, Shannon's Diversity, and Evenness indices. The spring diet is more diverse, with 16 plant species consumed versus just five and seven species in summer and autumn-winter respectively, with only five shared species among all seasons. Dietary overlaps are low between spring and other seasons and between summer and autumn. Conversely, there is moderate overlap between the summer diet and no difference between the autumn and winter diets. Trophic niche overlap is highest between spring, winter, and medium between other seasons, and there is a pronounced similarity between autumn and winter. The data we provide on seasonal variations in diet could be useful in developing management plans for tortoises and their natural habitat in arid lands with low productivity.