Morphological variation of Nymphaea (Nymphaeaceae) in European Russia

The morphological variability of the genus Nymphaea is described on the basis of detailed studies of fresh material from 49 populations in European Russia and southern Siberia. Macromorphological characters in the field (including analysis of leaf shape using geometrical morphometry), pollen size and exine sculpture have been analyzed. One polymorphic widespread species, N. candida, grows in most of European Russia. Nymphaea tetragona seems to be absent in the investigated waters and possibly in the whole central part of European Russia, whereas N. alba was found only in the Astrakhan Region (the delta of the River Volga). These three species are separated relatively well by several morphological characters in fresh plants. Nymphaea tetragona differs from N. alba and N. candida by the sculpture of the exine of the proximal part of the pollen grains, but the latter species do not seem to be differentiated by pollen characters. Size characters of Nymphaea leaves and flowers do not depend on organic content in water.