Scientists say that many of the world's plants are in danger of dying out – of becoming extinct. Dr Paul Smith said one in five of the world's plants is in danger. Botanic gardens contain about 100,000 species, including a third of all the world's endangered plants. Botanic gardens help to protect many endangered and rare plants. Dr Smith said: "This is the first time that we have [looked] at the wide range of plants grown, managed and conserved in botanic gardens. For the first time we know what we have and, perhaps more importantly, what is missing from botanic gardens."

Researcher Dr Samuel Brockington said botanic gardens were the best hope for saving the world's endangered plants. He said: "One-fifth of plant diversity is under threat, yet there is no technical reason why any plant species should become extinct." If we do not protect plants, people could have trouble finding food in the future. Dr Brockington said: "If we do not conserve our plant diversity, humanity will struggle to solve the global challenges of food…security…and climate change." Plants are in danger because of humans cutting down forests and climate change.