Medicago arborea is a plant species of the genus Medicago. Common names include moon trefoil, shrub medick, alfalfa arborea, and tree medick. It is found throughout Europe and especially in the Mediterranean basin, primarily on rocky shores among shrubby vegetation. It forms a symbiotic relationship with the bacterium Sinorhizobium meliloti, which is capable of nitrogen fixation. It is the only member of the genus Medicago which is used as an ornamental. M. arborea is sometimes misidentified as Cytisus, which it resembles.