The hybrid origin of Calamagrostis ×gracilescens (Poaceae) in Poland inferred from morphology and AFLP data

Abstract

The morphology of Calamagrostis canescens and C. stricta recorded in the Małopolska Upland (the vicinity of Zbijów Mały, ca. 10 km northeast of the town of Skarżysko-Kamienna, Central Poland) was examined due to intermediate individuals found in sympatric populations of these species. Both putative parents as well as individuals that appeared hybrid-like were found in an extensive, wet hay-meadow. Various vegetative and reproductive characteristics were studied to identify hybrids. Interestingly, Polish accessions of C. ×gracilescens exhibited some degree of morphological intermediacy but resembled C. stricta in spikelet morphology. Branching of the mid-culm, the number of nodes per culm, callus hair length and relative callus hair length are the best characters to distinguish the Polish C. ×gracilescens. AFLP analysis proved to be suitable for detecting recent hybridization events between C. canescens and C. stricta. Analysis of the Bayesian clustering analysis showed that C. ×gracilescens were subjected to gene flow from the C. canescens gene pool as well as from the C. stricta gene pool.