Conservation status of the unique population of Wenchengia alternifolia, an enigmatic plant endemic to Hainan Island, China

Wenchengia alternifolia (Lamiaceae) is a plant species endemic to Hainan Island, China. Since the 1930s it was known from only four collections and was believed to be extinct until a remnant population was rediscovered in 2010. We conducted further field surveys during 2010-2012 but located only one population, with 66 individuals. W. alternifolia is restricted to the c. 1,500 m(2) Shuangximu Valley, in a harsh microenvironment surrounded by plantations. As the population comprises < 50 mature individuals, we propose that W. alternifolia be categorized as Critically Endangered on the IUCN Red List, based on criterion D. We recommend that the remnant population and its habitat need urgent protection and monitoring and that ex situ conservation, for future reintroduction, should be implemented.