Nymphoides peltata (S. G. Gmel.) O. Kuntze (Menyanthaceae) at the border of geographic range: anatomical and morphological features

The results of the study of species Nymphoides peltata (S. G. Gmel.) O. Kuntze in the Arkhangelsk region (Northwest Russia) are presented. In the region the species population is located at the border of geographic range and therefore this species is considered to be rare. The species was first found on the left bank of the Severnaya Dvina River near Anfimovskaya village in 2014 and and was considered to be a floristic discovery. In 2017, the study was repeated to asess the dynamics of the main populational and organism characteristics of the species within the given habitat. The study includes a map of the species presence, its description and the main morphological and anatomical parameters of over- and underground vegetative organs of the plants.