Some 500 million people visit botanic gardens each year. As well as being popular visitor attractions, they are centres of learning and education, conducting valuable research and conservation work. The University of Cambridge study, published in the journal Nature Plants, identified gaps in the botanic collections of more than 1,000 institutions.
Many botanic gardens are in the Northern Hemisphere where tropical species are harder to maintain as they need to be grown in heated glasshouses. Tropical plants are best grown in their country of origin, but there are far fewer facilities in the Southern Hemisphere. Only 10% of global collections are dedicated to threatened species, suggesting botanic gardens could do more to preserve some of the world's most vulnerable plants.