This article discusses the morphometry, hydrochemistry, zooplankton, and macrophytes of three unique round lakes in the Nadym River basin (Western Siberia, Yamal-Nenets Autonomous Okrug (YNAO)). Their significant depths, weak lakeshore angularity, zero water color, and predominance of sulfates in the ionic composition are atypical for the northern taiga lakes of Western Siberia. Coastal aquatic vegetation is characterized by extremely low species richness with the dominance of Sparganium angustifolium, which is an indicator of highly transparent ultrafresh oligotrophic waters. Dominant complexes were formed in planktonic communities represented by 1–2 species with a high level of dominance. According to the level of development of total zooplankton biomass, the lakes are ultra- and oligotrophic.

The article contains data on localities of new and rare species and subspecies of vascular plants for the Polar Urals. The general distribution of Betula concinna is only approximately known. Botrychium alaskense is recorded in Western Siberia only in Altai. Crepis paludosa is lost in the Siberian flora. For 5 species and 1 subspecies (Alchemilla glomerulans, Astragalus gorodkovii, Botrychium boreale, B. lunaria, Castilleja arctica subsp. vorkutensis, Cystopteris fragilis) new localities were noted, confirming their occurrence or clarifying their distribution in the Polar Urals.

First records for Russia of naviculoid diatom from the Yaroslavl Region, and micromycetes from the Republic of North Ossetia — Alania, green alga for the Leningrad Region and Yamal-Nenets Autonomous Area, fragilarioid diatom for the Kaliningrad Region, red alga for the Nizhny Novgorod Region, cyanoprokaryota for the Leningrad Region and Chukotka Autonomous Okrug, and crustaceous red alga for the Autonomous Republic of Adjara of Georgia, macromycetes for the Leningrad Region, Khanty-Mansi Autonomous Area — Yugra, Republic of Tuva, Trans-Baikal Territory, myxomycetes for the Trans-Baikal Territory, lichens and allied fungi for the Murmansk and Tver regions, republics of Karelia and Tuva, Yamal-Nenets Autonomous Area, Altai and Khabarovsk territories, cyanolichen for the Urals and the Orenburg Region, mosses for the Lipetsk Region, republics of Ingushetia and Buryatia, Krasnoyarsk and Trans-Baikal territories are presented. The data on their localities, habitats, distribution are provided. The specimens are kept in the herbaria ALTB, GSU, IBIW, IRK, KPABG, LE, MHA, MW, NNSU, NSK, PZV, TBI, UUH, VU, YSU, and the Diatom collection of the Laboratory for Algology of IBIW RAS. Sequences of 16S, and 16S–23S ITS cyanobacterial RNA regions, ITS1-5.8S-ITS2 fungal and ITS1-2 moss nrDNA regions of some specimens have been deposited in the GenBank.

The article provides information about rare and newly described species for the flora of the Urals and adjacent territories, namely: Astragalus saphronovae Kulikov, Atraphaxis decipiens Jaub. et Spach., Carex amgunensis F. Schmidt, Galium densiflorum Ledeb., Jovibarba globifera (L.) J. Parn., Najas minor All., Potamogeton nodosus Poir., Pseudorchis albida (L.) Á. Löve et D. Löve, Salix myrsinites L., Veronica agrestis L. Essays include the information on the species ecology and short taxonomic notes.

Five species belonging to Lemnaceae family are known to grow in Siberia: Lemna gibba, L. minor, L. trisulca, L. turionifera, and Spirodela polyrhiza. Characteristics of their distribution in Siberia, bioecological characteristics, and facts of flowering and fruiting of Lemnaceae are provided in this paper. It has been shown that the generative reproduction of duckweed is not a rare phenomenon, and it is typical for all species of the family known in the region. The flowering is usually observed for L. trisulca and L. turionifera. However, some cases of flowering are known for S. polyrhiza. Almost all populations of L. gibba found in Siberia had flowering and fruiting plants. L. minor had a limited distribution in Siberia; cases of flowering are rare. The generative reproduction of duckweed is found only in freshwater bodies (0.1–0.7‰ salinity) with a water depth of 0.1–0.7 m, temperature of the surface water layer from +20 to +33°С, and pH from 5.96 to 9.30 units not obscured by tree–shrub and tall grass vegetation.