From 2007-2008 he was president of the Washington Academy of Sciences. He has been elected as a Fellow of the International Academy for the History of Pharmacy (1991), the Linnean Society (1997), the Washington Academy of Sciences (2003), the American Association for the Advancement of Science (2009), and the Royal Society of Medicine, UK (2010). He is the co-founder and current scientific director of the Institute for the Preservation of Medical Traditions and has been affiliated with the Smithsonian Institution from 2002 through 2016, where he was a historian of science in the botany department of the National Museum of Natural History. In September 2019, he was awarded the Kremers Award from the American Institute of the History of Pharmacy. He is one of the founders, and the principal investigator of the UNESCO Chair Plantae Medicinales Mediterraneae-Plants for Health in the Mediterranean Traditions, which was established at the University of Salerno, Italy, in 2020.
