The species of the genus Piliostigma despite the fierce anthropisation they face, still mark the agrarian landscape of Burkina Faso. This study aims to seize the different modes of adaptation in situ, the root system of species of the genus Piliostigma, so as to understand their mechanism of optimal adaptation. For this, the country was divided into transect zones going from the sub-Sahelian areas in the north to the sudanian ones in the south. In these areas clusters Piliostigma reticulatum and / or Piliostigma thonningii aged 25 to 30 years were studied. For each Piliostigma population considered, a soil profile was developed to determine the depth of the soil, the different soil horizons, and the morphology of the main root. Then all roots were carefully exposed taking into account the distribution of the soil horizons. Piliostigma’s root system does not depend on the phytogeographical area. The species of the genus Piliostigma have a twirling root system that adjusts to different types of soils. In shallow soils (0-40 cm), the main root, strongly tuberous, turns into lateral roots in contact with the armor. In moderately deep soils (0-40/60 cm), this root divides into a pitchfork that anchors itself in the armor. With these Piliostigma species, strong lateral roots develop at the second horizon while 60% of fine roots grow at the upper horizon. In addition, the volume of soil explored by Piliostigma’s root system is more important in the North-sudanian zone and significantly different from other climatic zones. These characteristics explain the adaptability of Piliostigma to the arid climate of Burkina Faso.