Barbula amplexifolia (Mitt.) A.Jaeger in Europe

Abstract

Barbula amplexifolia (Mitt.) A.Jaeger, formerly known only from Asia and North America, is reported from the Alps as new to Europe, being rather widespread in calcareous regions of Austria. It resembles a small B. crocea but differs in entire leaves and small, mostly ovoid, reddish-brown to purple axillary gemmae with slightly protuberant to smooth outer cells. Although the European population differs from the typical Indian material, we refrained from taxonomic segregation because of the enormous variability of the species in Asia and the existence of numerous intermediate morphs. Barbula amplexifolia probably reached the Alps vegetatively by means of gemmae across the cold Pleistocene steppes from Central Asia. This hypothesis is supported by the absence of male plants and sporophytes in the Alps and the relatively low level of morphological and anatomical variability, which seems to correspond well with the ecological conditions at the sites. It is an early pioneer on bare calcareous soil, nowadays probably much more frequent than earlier as a consequence of the extensive forest road construction of the last decades.