Islands have long held a fascination for scientists studying evolution and patterns of biodiversity, from Charles Darwin and Alfred Russell Wallace in the 19th century, to Robert MacArthur and E.O. Wilson in the 20th century, and continuing in the 21st century. Islands are often home to, for their size, a disproportionately large number of species with very narrow distributions, including single island endemics. They are also particularly vulnerable to the changes affecting the environment globally: habitat loss, climate change, and invasive species. Several island species are known to have been driven to extinction by human activity, with more perilously close to following them. At Kew, a key area of our work concerns the plant diversity of islands (UK, Madagascar, and the UK Overseas Territories in particular), the threats they face, and how best to conserve this unique life.