Orthotrichum alpestre, a new addition to the moss flora of Poland, with notes on O. schimperi (Orthotrichaceae: Bryophyta)

The occurrence of two epiphytic moss species, Orthotrichum alpestre Bruch & Schimp. and O. schimperi Hammar, in the moss flora of Poland is discussed. The former represents an entirely new country record based on a specimen collected from the Polish Eastern Carpathians, whereas the latter is reinstated as a member of the Polish moss flora. The complex and entangled taxonomic and nomenclatural history of O. schimperi is outlined, sources of its confusion are discussed, and two correctly determined specimens from Poland are cited. The two species are briefly characterized and illustrated, and a key to the genera and species of Polish orthotrichaceous mosses is presented.