The book "Ash" is a beautifully illustrated retrospective on the botanical and cultural aspects of the ash tree. It charts its evolution and geographical spread in the Northern Hemisphere over the last 44 million years and describes the 43 species that grace the planet today. Edward Parker also explores the botanical, cultural history, and medicinal uses of the tree, from its significance in ancient Indo-European cultures to its remarkable properties in treating Alzheimer's disease. Additionally, it examines current issues such as the devastating impact of the spread of the emerald ash borer and the fungal infection of ash trees in Northern Hemisphere forests.