Introduced populations of Pinguicula primuliflora (Lentibulariaceae) in Japan.
Pinguicula primuliflora C.E. Wood & R.K. Godfrey (Lentibulariaceae), a North American endemic butterwort species, has been present in the wild in Japan for a few decades. Based on voucher specimen studies and field observations by the author, at least six non-native locations were found, four of which have been confirmed to exist in Aichi and Okayama Prefectures. Although it is rather rare to find the species in the native habitats in the southeastern United States, it produces clonal plants and often forms large colonies in acid wetlands. It also behaves similarly in small acid wetlands in Japan. The population size of the species at a wetland in Bizen, Okayama Prefecture increased 200 times in the 15 years from 2004 to 2019. To prevent further expansion of the species in the country, it is necessary to uncover the current situation and ecology. The most recent information concerning P. primuliflora in Japan is provided here.