Actions aimed at reforesting arid areas around the world are becoming increasingly complex. In a recent study published in AoB PLANTS, Carevic et al. evaluated the physiological resistance to drought stress of Prosopis (mesquite) seedlings from different collection sites in the Atacama Desert, northern Chile. Their results show that seedlings from the most hyperarid habitats had higher tolerance to water stress than seed collected from less arid sites. The high variability in physiological responses to water stress at the interpopulation and intrapopulation levels provides a powerful seed selection tool for future reforestation programmes aimed at the early selection and genetic improvement of species of the Prosopis genus and at regenerating and preserving these endangered woodlands.