POLYPLOIDY OF NORTH EAST ASIA AQUATIC AND SEMIAQUATIC VASCULAR PLANTS

The chromosome numbers of aquatic and semiaquatic vascular plants growing in extreme North-East Asia, east of the Lena River, were analyzed. We have reviewed the information about the karyological peculiarity of the aquatic flora based on published data, including our own definitions. The karyological data are considered depending on the taxonomic position, distribution and ecological characteristics of the species. The chromosome numbers are known for 119 out of 123 species. There is no data on Zannichellia komarovii, Eleocharis termale, Stuckenia subretusa and Potamogeton sibiricus. In the aquatic flora of North-East Asia, the proportion of polyploids is higher (79%) than that reported for the entire Beringian flora (69%). We analyzed species for the presence of polyploidy depending on the type of area. Analysis by latitudinal groups revealed that all Arctic and hypoarctic species of aquatic plants are polyploids. The minimum proportion of polyploids is observed among arctoboreal species. Analysis by longitudinal groups revealed that the lowest proportion of polyploids was noted among species found only in Eurasia and absent in North America (61%), and it was the highest among pluriregional species (96%). The species of the families Cyperaceae, Lemnaceae, Ranunculaceae and Poaceae are characterized by a high level of variability in the number of chromosomes. The greatest variety of chromosome numbers is observed in the polymorphic species Caltha palustris s. l., Agrostis stolonifera, Dupontia fisheri s. l., Phragmites australis, in all species of the genus Eleocharis, and in Nymphaea tetragona, Acorus calamus, Calla palustris. The isolated cases of a high level of ploidy were found in the extreme northeast, at the northern borders of ranges, in 3 species - Hippuris vulgaris, Arctophila fulva and Beckmannia syzigachne. Only diploids are known in the families Equisetaceae, Typhaceae, Zosteraceae from the flora of North East Asia. We revealed the existence of several chromosomal races in Ranunculus gmelinii and Caltha palustris (Ranunculaceae) in the Magadan region; the distribution of chromosomal races is partly related to geographic location and partly to plant habitats. Rare karyotypes in these species are observed in aquatic forms with mainly vegetative reproduction, growing in non-freezing watercourses.