Humans have been using plants to heal since prehistory. Plants play a critical role in drug discovery, but can be hindered by the time and cost of collecting and screening large numbers of randomly selected plant samples. Current field identification is based on morphological phenotypes, which is not always reliable. One solution is to develop a device that can rapidly identify plants with the highest potential for bioactivity in the field. In a lab setting bioactivity can be determined with the use of a simple UV fluorescence assay. We hypothesize that a mobile darkroom with UV lights, that is field compatible, can be used to identify plants with higher levels of bioactive chemicals. Recent work demonstrated that sagebrush subspecies, whose leaves fluoresce blue when immersed in water and held under a UV light, have lower concentrations of potentially toxic chemicals when compared to the subspecies that do not fluoresce blue and appear to be a preferred food source for Sage Grouse. The device provides a controlled environment to visualize the plant’s UV fluorescence and the ability to document the fluorescence with a smartphone. This mobile darkroom allows researchers, while in the field, to identify plants containing fluorescent compounds leading to a more targeted collection of plants which saves time and resources in the drug discovery process.