The world’s botanic gardens must pull together to protect global plant biodiversity in the face of the extinction crisis, amid restrictions on wild-collecting, say researchers. A major study of botanic gardens around the world has revealed their struggles with one fundamental aim: to safeguard the world’s most threatened plants from extinction. Researchers analysed a century’s worth of records - from 1921 to 2021 - from fifty botanic gardens and arboreta currently growing half a million plants,