Genetic, cytological and morphological differentiation within the Balkan-Carpathian Sesleria rigida sensu Fl. Eur. (Poaceae): A taxonomically intricate tetraploid-octoploid complex

Reconstruction of relationships among populations of the morphologically polymorphic and taxonomically intricate Sesleria rigida sensu Fl. Eur. based on Amplified Fragment Length Polymorphisms (AFLPs) revealed four clearly differentiated genetic groups that did only partly follow recent taxonomic concepts, but were strictly allopatric. While some of the previ- ously described taxa constitute distinct genetic entities, others have no taxonomic value. Synthesizing our AFLP data with ploidy-level information obtained from all genetically investigated individuals as well as with chromosome counts revealed that tetraploid individuals prevail, while octoploids occur only within S. filifolia. Lack of AFLP divergence between tetra- and octoploids suggests an autopolyploid origin of the latter. The genetic differentiation pattern was reflected by morphological differentiation, allowing for a taxonomic revision of the constituents of S. rigida sensu Fl. Eur. resulting in recognition of the four species S. achtarovii, S. filifolia, S. rigida, and S. serbica.