First record of Potamogeton×salicifolius for Italy, with isozyme evidence for plants collected in Italy and Sweden

Abstract

Potamogeton×salicifolius, a hybrid between P. lucens and P. perfoliatus, is identified as a new taxon for Italy. This is the first record of this hybrid from southern Europe. The Italian sample was studied in cultivation and compared with a living specimen of P.×salicifolius from Sweden, where the hybrid is rather widespread. In addition to morphological features, the most compelling evidence for the hybrid origin of these plants came from the isozyme analysis. The additive “hybrid” banding patterns of the five enzyme systems studied indicate inheritance from P. lucens and P. perfoliatus. The distribution of this hybrid in Europe coincides with the areas most severely affected by the Late Pleistocene glaciation. The relationships between environmental conditions, history of the habitat and rise of hybrids are discussed.

Key words:

• Taxonomy
• morphology
• Mediterranean
• electrophoresis
• hybridization
• postglacial lakes

Acknowledgements

I am especially grateful to Ivana Plačková and Karin Brigitte Šrámek de Kott, who performed the isozyme electrophoresis. I express my thanks to Jitka Štěpánková for her help during fieldwork, to Ondřej Dvořák and Vojtěch Zavadil for taking care of the cultivated Potamogeton material and to Tony Dixon for improving the English of the manuscript. The research was supported by grant nos. 206/03/P156 and 206/06/0593 from the Grant Agency of the Czech Republic and the Institutional Long-Term Research plan nos. AV0Z60050516 of the Academy of Sciences of the Czech Republic.