This virtual issue highlights integrative research exploring 'Diversity through time': the connection between evolutionary history and spatial distribution, either at phylogenetically shallow levels, e.g. population genetics/ phytogeography, or phylogenetically deeper levels, e.g. phylogeny and paleontology. These studies provide not only crucial advances towards the reconstruction of the tree-of-life, but also elucidate details of the mechanisms and processes. By doing so, they provide empirical evidence essential to urgently advance our understanding of the response of biodiversity to past crises and climatic events. Understanding the evolutionary potential of different branches of the tree-of-life, such as liverworts, ferns, fungi, and angiosperms, is crucial to predict the impact of the anthropogenic biodiversity crisis on the maintenance of biodiversity in a world transformed by humanity.

This virtual issue was assembled to celebrate the XIX International Botanical Congress held in Shenzhen - the first IBC to be held in China. This landmark event highlights the rapid progress made in establishing the People’s Republic of China as one of the globally-leading research nations, and also provides a unique opportunity to explore collaborative research, involving botanists from all nations, to tackle the pressing needs to manage the conservation of plant diversity.