Poa riphaea, an endangered stenoendemic species in the Hrubý Jeseník Mts (Eastern Sudetes).

The taxonomy, nomenclature, geographic distribution, karyology, morphology and isozyme variation in Poa riphaea, a supposed endemic species in central Europe, were studied. We especially focused on resolving the long-standing uncertainty about its relationship with P. laxa by assessing morphological and isozyme data. Attention was also paid to the morphological differention between P. riphaea and P. nemoralis from the highest parts of the Hrubý Jeseník Mts. Our isozyme analysis did not reveal any within-population genetic variability in the last remaining population of P. riphaea at the summit of Mt Petrovy kameny. The reasons for the variability in its morphology are discussed in the context of environmental conditions. The octoploid chromosome number of P. riphaea has been, probably, for the first time, reliably determined to be 2n = 56. We also present a map of the species’ historical and recent distribution. In addition to the sole recent locality at Mt Petrovy kameny, we have confirmed two historical localities (Tabulové skály rock and Velká Kotlina glacial cirque). We have selected a neotype for the name P. riphaea.