AbstractThe roots of Cedrus atlantica grown in a cedar forest soil under gnotoxenic conditions formed a mycorrhizal association with Tricholoma tridentinum Singer var. cedretorum Bon when this fungus was inoculated into the soil as a mycelial form. This association was not observed when plants were grown on an artificial substrate or when mycelium was immobilized in a calcium alginate gel. The influence of host receptiveness, fungal survival and cultural conditions on the mycorrhizal infection of C. atlantica is discussed.