The Yunnan-Kweichow Plateau in Guizhou, China, is famous for its plant diversity. However, unlike in Yunnan, where there have been many explorations for plants, large areas in Guizhou remain to be investigated. Rhododendron liboense Z. R. Chen & K. M. Lan, an evergreen tree of the Ericaceae family, is only known from a single population of 35 individuals growing on a karst mountain in Libo county, south-east Guizhou. It was categorized as Critically Endangered on the Red List of Rhododendrons (Gibbs et al., 2011, The Red List of Rhododendrons, Botanic Gardens Conservation International), and as Critically Endangered on the Chinese Higher Plants Red List (Qin et al., 2017, Biodiversity Science, 25, 696–744).
To secure more information on R. liboense three field surveys were carried out in Libo County during 2017–2018 with the support of Botanic Gardens Conservation International (grant no. BGCI30415). In addition to the type location on Donghua mountain in Maolan National Nature Reserve, two additional populations of R. liboense were located. In April 2017 a population of 15 plants (with four flowering) was found in Xizhu, c. 10 km from the type location of R. liboense. In March 2018 a population of 36 plants (with 23 flowering) was found in Dongdao, c. 20 km from the type location. These finds bring the total number of known individuals to 86. The habitat of the two newly located populations is similar to that of the type location, where R. liboense grows on steep karst mountains, but outside Maolan National Nature Reserve.
In addition, 300 seedlings of R. liboense, propagated from seeds collected from the Donghua population in November 2016, are available for ex situ conservation. At least 100 seedlings will be planted in 2018 in the Rhododendron garden of Guizhou Minzu University, to assess adaptation. Given the species’ apparently low fruit production and that two of the three known populations are unprotected, additional in situ conservation is required for this rare endemic Rhododendron. We are now discussing with local government officials potential in situ conservation actions for populations of R. liboense outside Maolan National Nature Reserve. Research on the pollination biology and population genetics of R. liboense is planned, to support the conservation of the species.