Eight species, new for science, i.e.: Lobothallia gangwondoana S. Y. Kondr., J.-J. Woo et J.-S. Hur and Phyllopsora dodongensis S. Y. Kondr. et J.-S. Hur from South Korea, Eastern Asia, Ioplaca rinodinoides S. Y. Kondr., K. K. Ingle, D. K. Upreti et S. Nayaka, Letrouitia assamana S. Y. Kondr., G. K. Mishra et D. K. Upreti, and Rusavskia indochinensis S. Y. Kondr., D. K. Upreti et S. Nayaka from India and China, South Asia, Caloplaca orloviana S. Y. Kondr. and Rusavskia drevlyanica S. Y. Kondr. et O. O. Orlov from Ukraine, Eastern Europe, as well as Xanthoria ibizaensis S. Y. Kondr. et A. S. Kondr. from Ibiza Island, Spain, Mediterranean Europe, are described, illustrated and compared with closely related taxa. Fominiella tenerifensis S. Y. Kondr., Kärnefelt, A. Thell et Feuerer is for the first time recorded from Mediterranean Europe, Huriella loekoesiana S. Y. Kondr. et Upreti is provided from Russia for the first time, and H. pohangensis S. Y. Kondr., L. Lőkös et J.-S. Hur for the first time from China, Phoma candelariellae Z. Kocakaya et Halıcı is new to Ukraine, and Staurothele frustulenta Vain. is recorded from the Forest Zone of Ukraine for the first time. Twelve new combinations, i.e.: Bryostigma apotheciorum (for Sphaeria apotheciorum A. Massal.), Bryostigma biatoricola (for Arthonia biatoricola Ihlen et Owe-Larss.), Bryostigma dokdoense (for Arthonia dokdoensis S. Y. Kondr., L. Lőkös, B. G. Lee, J.-J. Woo et J.-S. Hur), Bryostigma epiphyscium (for Arthonia epiphyscia Nyl.), Bryostigma lobariellae (for Arthonia lobariellae Etayo), Bryostigma lapidicola (for Lecidea lapidicola Taylor), Bryostigma molendoi (for Tichothecium molendoi Heufl. ex Arnold), Bryostigma neglectulum (for Arthonia neglectula Nyl.), Bryostigma parietinarium (for Arthonia parietinaria Hafellner et Fleischhacker), Bryostigma peltigerinum (for Arthonia vagans var. peltigerina Almq.), Bryostigma phaeophysciae (for Arthonia phaeophysciae Grube et Matzer), Bryostigma stereocaulinum (for Arthonia nephromiaria var. stereocaulina Ohlert), are proposed based on results of combined phylogenetic analysis based on mtSSU and RPB2 gene sequences. Thirty-one new combinations for members of the genus Polyozosia (i.e.: Polyozosia actophila (for Lecanora actophila Wedd.), Polyozosia agardhiana (for Lecanora agardhiana Ach.), Polyozosia altunica (for Myriolecis altunica R. Mamut et A. Abbas), Polyozosia antiqua (for Lecanora antiqua J. R. Laundon), Polyozosia bandolensis (for Lecanora bandolensis B. de Lesd.), Polyozosia behringii (for Lecanora behringii Nyl.), Polyozosia caesioalutacea (for Lecanora caesioalutacea H. Magn.), Polyozosia carlottiana (for Lecanora carlottiana C. J. Lewis et Śliwa), Polyozosia congesta (for Lecanora congesta Clauzade et Vězda), Polyozosia eurycarpa (for Lecanora eurycarpa Poelt, Leuckert et Cl. Roux), Polyozosia expectans (Lecanora expectans Darb.), Polyozosia flowersiana (Lecanora flowersiana H. Magn.), Polyozosia fugiens (for Lecanora fugiens Nyl.), Polyozosia invadens (for Lecanora invadens H. Magn.), Polyozosia juniperina (for Lecanora juniperina Śliwa), Polyozosia latzelii (for Lecanora latzelii Zahlbr.), Polyozosia liguriensis (for Lecanora liguriensis B. de Lesd.), Polyozosia massei (for Myriolecis massei M. Bertrand et J.-Y. Monnat), Polyozosia mons-nivis (for Lecanora mons-nivis Darb.), Polyozosia oyensis (for Lecanora oyensis M.-P. Bertrand et Cl. Roux), Polyozosia percrenata (for Lecanora percrenata H. Magn.), Polyozosia persimilis (for Lecanora hagenii subsp. persimilis Th. Fr.), Polyozosia poeltiana (for Lecanora poeltiana Clauzade et Cl. Roux), Polyozosia prominens (for Lecanora prominens Clauzade et Vězda), Polyozosia prophetae-eliae (for Lecanora prophetae-eliae Sipman), Polyozosia salina (for Lecanora salina H. Magn.), Polyozosia schofieldii (for Lecanora schofieldii Brodo), Polyozosia sverdrupiana (for Lecanora sverdrupiana Øvstedal), Polyozosia torrida (for Lecanora torrida Vain.), Polyozosia wetmorei (for Lecanora wetmorei Śliwa), Polyozosia zosterae (for Lecanora subfusca? zosterae Ach.)) are proposed.

Results of the conducted botanical surveys in the Forest-Steppe part of Zhytomyr Region are provided. Nine alien taxa (mainly xenophytes) new for the flora of the Right Bank Forest-Steppe have been identified: Allium altissimum, Amaranthus deflexus, Aphanes arvensis, Artemisia umbrosa, Crataegus sanguinea, Epilobium pseudorubescens, Erigeron strigosus, Polygonum calcatum, and Silene coronaria. Localities of these species are described and botanical-geographical comments are provided for most of taxa. There are also 64 taxa newly reported for the Forest-Steppe part of Zhytomyr Region, of which 31 are native plants, 32 – alien plants, and 1 species of unidentified origin. Twelve taxa are rare and protected at different levels. Invasive plants in need of monitoring are identified among newly reported species. According to the new data, flora of the Forest-Steppe part of Zhytomyr Region includes more than 1320 taxa of vascular plants. An important result was the discovery at the border of Zhytomyr Polissya and the Right Bank Forest-Steppe of localities of five expanding species of the genus Rubus with predominantly Central European ranges: R. bertramii, R. gracilis, R. hirtus, R. montanus, and R. plicatus. Expansion of these species of blackberries in the eastern direction within the territory of Northern Ukraine is associated with natural migration and is probably caused by the gradual climate warming.

The article presents the results of studies of a series of species identifications of the genus Lemna (Lemnaceae) conducted in 2019. Duckweed samples were taken from eight localities in the northern regions of Ukraine and identified to species using morphological and molecular markers (barcoding). A new alien species of duckweed for Ukraine—lesser duckweed (Lemna aequinoctialis Welw.)—was discovered, to which this study is devoted. All other samples belonged to Lemna minor. The article presents the most complete description of the distribution of L. aequinoctialis Welw. in Europe, and also contains updated data on the species distribution of duckweeds in Ukraine. Six species of the genus Lemna are now known in Ukraine—three native and three alien. The ecological requirements of L. aequinoctialis are similar to those of L. minor. We examined the morphological similarities and differences between these species, and confirmed the results by molecular barcoding using the plastid regions of the atpF‐atpH and psbK‐psbI intergenic spacers.

The investigation results of the transformer species participation (Echinocystis lobata (Michx.) Torr. & A. Gray, Heracleum sosnowskyi Manden., Impatiens glandulifera Royle, I. parviflora DC., Reynoutria japonica Houtt., Robinia pseudoacacia L.) in different plant communities of the Ukrainian Polissya (Forest zone of Ukraine) are presented. All the abovementioned species are strong edificators in the region that can significantly change important species composition parameters of communities and character of landscape.

Information about floristic record of Erechtites hieracifoliа (L.) Raf. ex DC. (Asteraceae Bercht. & J. Presl) at the territory of the Chernobyl Radiation and Ecological Biosphere Reserve and National Nature Park "Нolosiivsky", new for the Kyiv Polyssia alien species was presented. This species has north american origin, according to the time of arrival it is kenophyte, according to the skidding method – xenophyte, on naturalization level – kolonophyte. Firstly in the region of study this species was collected in 2018 in vicinities of former village Ilovnitsa (northern part of the village) of Ivankov district of Kyiv Oblast. Later, in 2019 E. hieracifoliа was noted in two another sites of biosphere reserve (vicinities of former village Klyvyny of Ivankiv District, Kyiv Region and former village Kamianka of the same administrative units). Total revealed more than 60 species plants, in vegetative state (prevailed) and also in generative state. Plants were noted sporadically on forest edges and roads in composition of unformed plant communities. In 2019 this species was also found on the territory of National Naturе Park "Нolosiivsky" (Sviatoshin-Bilychі branch) where individuals of the species were found singly or in small groups (5–10 plants). In total, 60 plants of E. hieracifoliа were noted here. Probably they came to the study region recently – some years ago, skid occurred on high roads which plants used as wind corridors flanked by forests, and also on local ways; it is possible that diaspores distribution is carried out also by birds. Schematic map of species distribution in the region was presented. Data about primary and secondary areas of the E. hieracifoliа, its ecological and coenotic peculiarities were presented. The main stages of history of skidding and further distribution of the investigated species in Ukraine were reconstructed; the main directions of it distribution is connected with northern and western regions of the country. Currently, the species tends to actively spread into another regions of Ukraine. In Europe it belongs to invasive species and demands control of spread.

Radioactive contamination of the aboveground phytomass of marsh Labrador tea (Ledum palustre L.) in different periods after the Chernobyl accident was studied. Marsh Labrador tea is widely used in official and folk medicine. The studied species grows in over-moistened pine (less mixed) forests and open oligotrophic and mesotrophic marshes. It was found that in the first four years since the beginning of observations (1991), the magnitude of the specific activity of 137 Cs in above-ground vegetative phytomass of marsh Labrador tea, depending on a permanent sample area (PSA), decreased by 1.2-1.4 times. After 10 years, it decreased by 1.6-1.7 times, after 16 years by 1.9-2.1 times, after 21 years by 2.7-3.1 times, and after 27 years by 3.1-6.5 times. An increase in the magnitude of transitions factors was also observed on all PSA over time. Thus, the minimal increase within 1991-2018 was recorded in PSA 11-by 1.2 times and on PSA 13-by 1.4 times. The maximum decrease in the magnitude of transition coefficient was observed in PSA 16-by 2.7 times, in PSA 15-by 3.0 times, and in PSA 18-by 2.0 times. It was found that marsh Labrador tea belongs to the group of plants that are characterized by the high content of 137 Cs in the above-ground vegetative phytomass. Within the observation period (1991-2018), this content significantly exceeds the admissible levels of radionuclide content in plant medicinal raw materials that are used for manufacturing medical preparations. In the PSA with maximum magnitudes of soil contamination density (400.5±50.73 kBk•m-2) this excess made up 158.4 times in 1991, and 33.7 times (166.9±23.56 kBk•m-2) in 2018. For 27 years of observations, there has been a decrease in the density of radioactive soil contamination by 2.1-2.7 times, which is due to radionuclide decomposition, its vertical migration in the soil, and towards the components of forest ecosystems

Установлено, що продовжується інтенсивне надходження 137 Cs до надземної частини фітомаси та ягід чорниці. Дослідження проведено на дерново-середньопідзолистих, піщаних ґрунтах вологих суборів. Коефіцієнти переходу 137 Cs (м 2 кг -1 10 -3 ) в надземну частину чорниці (17 -53) значно більші, ніж в ягоди (4 -8). Виявлено зниження рівнів радіоактивного забруднення 137 Cs надземної фітомаси та ягід чорниці за період спостережень. Протягом 1991 -2016 рр. питома активність 137 Cs в ягодах чорниці знизилася у 3,7 -8,3 раза, у надземній частині -у 8,2 -19,2 раза. У верхньому 0 -10-см шарі мінеральної частини ґрунту вологих суборів міститься 69,9 % від сумарної активності радіонукліда в ґрунті. Найбільша величина цього показника встановлена для 0 -2-см шару мінеральної частини ґрунту -28,4 ± 2,0 %. Найбільша питома активність 137 Cs встановлена для розкладеної частини лісової підстилки та верхнього 0 -2-см шару гумусово-елювіального горизонту.

and conservation of rare fern species of rocky biotopes in the Polissya part of Zhytomyr Region.