Gerould S. Wilhelm is an American botanist and lichenologist. He is known as author of several floras of the Chicago Region and the development of the Floristic Quality Assessment methodology, a tool to assess the integrity of natural areas. He is the director of research at Conservation Research Institute, a nonprofit organization "dedicated to the promotion of planning, design, restoration, and long-term management of sustainable ecological systems in built and natural environments through applied research, education, and outreach."