How selfing and intra- and interspecific crossing influence seed set, morphology and ploidy level in Euphrasia: An experimental study of species occurring in the Alps of Switzerland

Annual alpine species rely on selfing rather than on cross-pollination for successful reproduction. However, insect visits may occasionally cause cross-pollination not only within but also between closely related species. The aim of this study was to investigate four species of Euphrasia for their efficiency in spontaneous selfing and their success in intra- and interspecific crossing. We used the seed sets that followed spontaneous selfing and artificial cross- and selfpollination to measure the breeding success. We compared the morphological characters of species and hybrids and determined their ploidy level using flow cytometry. We verified the hybridogenous origin of plants resulting from interspecific crosses using RAPD banding patterns. While spontaneous seed set was high in the two small-flowered species, seed set in the large-flowered species was small and affected by external circumstances. We obtained F1 and F2 hybrids from interspecific crosses of two diploid species and detected polyploid individuals in both generation