The Algerian Sahara Desert which occupies more than 80% of the Algerian territory represents an ecosystem generally hostile to the spontaneous survival of living organisms. There are always geomorphologic patterns (camel pastures) relatively favourable to the proliferation of a very scattered plant species that are well adapted to the desert conditions. The dromedary is the only domestic species able to thrive under such conditions and benefit from this type of vegetation, which constitutes its main dietary source. The nutritional study of these plants shows a chemical composition reflecting the conditions of the desert. It is characterized by richness in parietal compounds and crude fibre (up to 75 and 50%) and general low content in total nitrogenous matter (4 %). However, a large variability between species related mainly to their different ecotypes and secondly to their soil conditions is observed. The in vitro digestibility is variable also depending on the species studied (22 to 37%), and its values are positively correlated with TNM and negatively with parietal compounds. Besides, the time study allows observing high contents in parietal compound in summer and relatively high contents in TNM in spring, so engendering the best digestibility in spring and lowest in summer.