Unclear resource background seriously restricts biodiversity conservation of Rhododendron in China

China harbors more than 600 species of Rhododendron and is thus considered a modern distribution and differentiation center of the genus. Based on the Red List of Rhododendrons, Red List of China's Higher Plants, and Threatened Species List of China's Higher Plants, as well as recent investigations, we re-analyze the threatened status of Rhododendron according to the criteria of the IUCN Red List and plant species with extremely small populations. As a result, among the 12 critically endangered Rhododendron species, four are no longer Critically Endangered, one is Data Deficiency, and one is Extinct. In total, nearly 20% of the Rhododendron species are threatened in China, and another one third are data deficient. Thus, the unclear resource background seriously restricts the biodiversity conservation of Rhododendron in China. Future research should include comprehensive investigations on Rhododendron resources, and urgent action should be taken to protect critically endangered species with extremely small populations. Fundamental research and landscape applications should also be strengthened.