Water scarcity and waste mismanagement are global crises that threaten the health of populations worldwide and a sustainable future. In order to help mitigate both these issues, a solar desalination device composed entirely of fallen leaves and guar - both natural materials - has been developed and demonstrated herein. This sustainable desalinator realizes an evaporation rate of 2.53 kg m-2 h-1 under 1 sun irradiance, and achieves consistent performance over an extended exposure period. Furthermore, it functions efficiently under a variety of solar intensities and in high salinity environments, and can produce water at salinities well within the acceptable levels for human consumption. Such strong performance in a large variety of environmental conditions is made possible by its excellent solar absorption, superb and rapid water absorption, low thermal conductivity, and considerable salt rejection abilities. Composed primarily of biowaste material and boasting a simple fabrication process, this leaf-guar desalinator provides a low-cost and sustainable avenue for alleviating water scarcity and supporting a green path forward.