Genetic, morphometric and microhabitat data reveal that papillose feather grasses in the Eastern Alps (Stipa epilosa auct.) do not constitute a separate taxonomic entity

Feather grasses (Stipa) are among the most typical constituents of steppe vegetation. Enigmatic S. epilosa, which was suggested to occur in various parts of the Alps, differs from common S. eriocaulis in the micromorphology of the cross section of its leaves. The rib flanks of the upper leaf surface lack the dense hairs typical of S. eriocaulis; instead, they are covered by short cone-shaped papillae. Populations of Stipa in the Vinschgau Valley in South Tyrol and the upper Inn Valley and Wipptal Valley in North Tyrol were studied using morphometric analysis of leaf cross sections, AFLP fingerprinting and microhabitat analyses. The following specific questions were addressed: (i) Is S. epilosa genetically divergent from S. eriocaulis? (ii) Are micromorphological differences between S. eriocaulis and S. epilosa consistent? (iii) Are there microhabitat differences between S. eriocaulis and S. epilosa, potentially reflecting adaptation of papillose and hairy individuals to different environmental conditions? First, this study revealed no genetic difference between S. eriocaulis and S. epilosa in the Eastern Alps. Second, there is a continuum in the variation in hair lengths from typical S. epilosa to typical S. eriocaulis, which makes it difficult to differentiate between two discrete groups. Finally, no microhabitat differences were recorded between papillose and hairy individuals. From a taxonomic point of view, our integrative approach combining genetic, morphometric and microhabitat data failed to support the hypothesis that S. epilosa is an independent taxon in the area studied.