Rediscovery of Primulabrachystoma (Primulaceae), a rare species endemic to Gaoligong Mountain of Chinese-Burma frontier

The rare Primulabrachystoma W.W.Sm. is an endemic species confined to Gaoligong mountain of Chinese-Burma frontier, which has been rediscovered from the same region after nearly 100 years. In total, 11 specimens from Gaoligong Mountain have been found in the herbaria worldwide, since its first collection in 1920 by Farrer, Reginald John. Previously, this species was described as homostylous but our finding shows the species also exhibited heterostyly. A complete description of the species, the distribution, morphological comparison and identification key from closely related species are provided here. An assessment of its conservation status suggests that the species is ‘Endangered’ (EN).