Hybrids of broad-leaved Potamogeton (Potamogetonaceae) are common in Siberia

Abstract

We have summarized the distribution of Potamogeton hybrids in Siberia based on extensive field and herbarium work. Four most common broad-leaved Potamogeton hybrids, P. × angustifolius, P. × nitens, P. × salicifolius and P. × sparganiifolius, and one very rare P. × cognatus occur in 178 localities, of which 108 are newly reported ones. Hybrids are mostly found in areas where both parental species are common and the research activity is high. Unlike Europe where both hybrid diversity and frequency of occurrence increase with latitude, in Siberia both diversity and frequency peak south of 60° N, which is the northern distribution limit for many Potamogeton species due to the more severe continental climate of Siberia. Habitat preferences of the hybrids depend on the dominant type of water bodies and the suitability of environmental conditions in the area. In the southern lowlands, most records of hybrids are made in rivers. At higher elevations (>800 m a.s.l.) or at the northern and western distribution limits, Potamogeton hybrids were found in lakes or stagnant water bodies.