Paul Smith is secretary-general of Botanic Gardens Conservation International (BGCI). BGCI leads the Global Tree Assessment and recently published the “State of the World’s Trees Report” showing that one-third of the world’s tree species are threatened with extinction. Prior to joining BGCI, Smith was head of the Millennium Seed Bank of the Royal Botanic Garden, Kew. He is editor of The Book of Seeds, also published by the University of Chicago Press.