Acacias are spectacular angiosperms grouping single canopy species to those of tropical forests. Easy growth, hardiness and drought resistance of these Australian Wattle trees give them variable and great economic importance. Indeed, among other they produce, wood, edible seeds, gums and provide a valuable source of high quality fodder, rich in protein for subsistence and commercial production of livestock because they provide foliage during dry periods in the absence of herbaceous species. In addition, they contribute to the warmer climate of arid and semi-arid areas by reducing evaporation and creating a shadow that slows the soil drying and provide the setting and coastal sand dunes with their lateral root system that promotes better maintenance of the sand particles cohesion. Moreover, their ability to develop a dual symbiosis with Rhizobium bacteria and mycorrhizal fungi confers ecological importance. Indeed, they provide soil enrichment and improvement of soil fertility due to their ability to fix atmospheric nitrogen and to explore deep horizons of the soil by their roots. All these factors make it an economic resource of a great environmental and social importance, especially in arid and semi-arid areas, and an excellent candidate for reforestation of Mediterranean areas.