Disjunction between East Asian and eastern North American plants has been recognized since the time of Darwin. Although there is considerable evidence for congruent vicariance associated with late Neogene/Quaternary cooling among angiosperms, similar studies among specific fern families (e.g., Osmundaceae Martinov) have appeared incongruous with this pattern. Pteridologists continue to debate whether long-distance dispersal of wind-blown spores could have produced intercontinental disjunctions among ferns. To date, however, state-of-the-art historical biogeographical approaches have not been applied to this problem. In this investigation, multiple chloroplast gene (rbcL, atpA, atpB, and matK) sequences for ferns in the family Onocleaceae Pic. Serm. are drawn from GenBank, including those from the recently sequenced chloroplast genome of the East Asian fern O. sensibilis L. var. interrupta Maxim., and used to create molecular phylogenies using Bayesian (BEAUTi and BEAST) techniques. Using contemporary approaches for relaxed molecular clock divergence time estimation with fossil calibration, divergence time estimates for East Asian and eastern North American populations in the Onoclea sensibilis species complex are consistently reconstructed as the Pliocene (ca. 5 – 3.4 Ma), and the best-fitting historical biogeographic model is a DIVA-like (exclusively vicariant) model using BIOGEOBEARS in RASP4, with a low probability of peripatry. Accordingly, these molecular and fossil data appear congruent with the pattern observed among angiosperms, despite the propensity for long-distance dispersal of wind-blown spores in pteridophytes. The lack of evidence for peripatry in this lineage may be related to the presence of short-lived green spores in onocleoid ferns; however, this hypothesis requires further investigation.

The ferns of the genus Arctopteris from the Cretaceous deposits of the North-East of Russia (the Aigur, Galimov, Krivorechenskaya, Arman, Amka, Gidra, Kananyga, Tylpegyrgynai, Poperechnaya, Emuneret, Barykov and Rarytkin formations) were re-examined. In the result eight species were included in this genus: A. lenaensis Vassilevskaja (Aptian), A. heteropinnula Kiritchkova (lower–middle Albian), A. kolymensis Samylina (lower–middle Albian), A. obtusipinnata Samylina (lower–middle Albian), A. rarinervis Samylina (lower Albian-Coniacian), A. penzhinensis E. Lebedev (Turonian-Coniacian), A. ilirnensis Golovneva (Turonian-upper Santonian) и A. rarytkinensis Vassilevskaja (Coniacian-Danian). Species A. microphylla Philippova and A. rarinervis are united under the name A. rarinervis.

The leaf epidermis of four species of Gnetum L. and four species of the Jurassic Bennettitales (Nilssoniopteris Nathorst and Ptilophyllum Morris) were studied. In addition to the description of qualitative characters, the analysis of various quantitative characters was carried out using statistical methods. Coefficients of variation for quantitative characters of the epidermal structure in Gnetum range from 6.4 to 24.0%, in Ptilophyllum from 15.7 to 63.5%, in Nilssoniopteris from 18.0 to 39.9%. The sinuosity of tangential cell walls of the epidermal cells in the upper and lower epidermis is the stable character in both groups of plants (Cv ≤ 18.0%). In Ptilophyllum and Gnetum, the length of stomata demonstrates a low level of common variability (Cv ≤ 16.8%). A significant range in the coefficients of variation in both Gnetum and the studied genera of Bennettitales is typical for the number of epidermal cells per 1 mm2 of the upper and lower epidermis (17.5% ≤ Cv ≤ 31.9%), the area of the epidermal cells of the upper and lower epidermis (21.2% ≤ Cv ≤ 63.5%), and the number of stomata per 1 mm2 of the epidermis (29.3% ≤ Cv ≤ 39.9%). The similarity in the correlation structure of epidermal characters is manifested in the correlation between sinuosity of tangential cell walls of epidermal cells, the number of stomata per 1 mm2 of the epidermis, and size of epidermal cells, as well as between the length of the stomata and the number of epidermal cells and also between the stomatal index and the number of cells in epidermis. In Gnetum, the ratio of the number of differentiated stomata correlates with the number of aborted stomata per 1 mm2 of epidermis. In N. angustifolia and P. caucasicum, the number of stomata correlates with the number of papillae per 1 mm2.

A catalogue of fossil plants collected and/or described by the famous Russian palaeobotanist, an employee of the Komarov Botanical Institute RAS, Natalia Snigirevskaya is presented. The materials are stored in the Laboratory of Palaeobotany of the BIN RAS. References are provided to publications based on these collections. The catalogue is accompanied by images of some holotypes made with modern equipment. A short essay on the life and work of Natalia Snigirevskaya precedes the catalogue.

A general characterization of the Late Cretaceous floras of the Zeya-Bureya Basin is provided based on floristic assemblages from Russia (Amur Region) and China (Heilongjiang Province). Four phases of floral evolution were revealed: the Turonian-Coniacian (the Sutara flora), the Santonian (the Yong’ancun and Middle Kundur floras), the Campanian (the Taipinglinchang and Late Kundur floras) and the late Maastrichtian (Bureya flora). This long paleofloral succession provides possibility for investigation of different trends in the evolution of the Late Cretaceous taxa, flora, and climate.

Dispersed cuticles of plants from coals of the Middle Jurassic Ulugkhem Formation (locality 229 near Mount Begreda, Ulug-Khem Basin, Republic of Tyva) were studied. As a result of the study of mesofossils using light and scanning electron microscopes, it was found that the coals are composed mainly of the remains of ginkgophytes. They are represented by the leaves of Pseudotorellia cf. angustifolia Doludenko, the female reproductive organs of this plant Umaltolepis sp., as well as the leaves of Eretmophyllum neimengguensis Li, Sun, Wang, Dilcher, Tan, Li, Na. The conifers played subordinate role. The palynospectrum of the coal seam is dominated by the spores of ferns; bisaccate and monosulcate pollen are next in importance. Thus, ginkgophytes and ferns predominated in the Middle Jurassic swamp communities in the Ulugh-Khem Basin. For the first time, the coal-forming role of the genus Eretmophyllum was revealed. The Middle Jurassic flora of Tyva is similar to the floras of the Kansk-Achinsk and Irkutsk basins of Eastern Siberia, Angren Basin of Uzbekistan, and the Ordos Basin of Inner Mongolia, China by predominance of Pseudotorellia. The vegetation was clearly differentiated into the lowland and the slope one. In the latter the leptostrobaleans, ginkgoaleans, and conifers were represented. Pseudotorellia is one of the main components of swamp plant communities in the more northern regions: in the Ulug-Khem and Irkutsk basins, and in the Aban and Pereyaslovka coal fields of the Kansk-Achinsk Basin. This genus disappears in the Nazarovo coal field of the Kansk-Achinsk Basin, being replaced by the leptostrobaleans. Here the compositions of swamp and slope communities practically do not differ. The Late Mesozoic swamp plant communities were characterized by conservatism, as well as by extreme sensitivity to environmental changes, which apparently developed because of their existence in the same conditions of high humidity. Degradation of the swamps led to the disappearance of swamp plant communities.

A new fern Birisia mandshurica, sp. nov. (Dicksoniaceae) from the lower–middle Albian Frentsevka Formation of southern Primorye, Far East of Russia is described. This species is characterized by short-creeping rhizomes with closely spaced stipes and bipinnate fronds with narrow linear pinnules. A reconstruction of B. mandshurica is proposed. It comes from the autochthonous locality of ferns and herbaceous angiosperms and was a part of pioneer open community, which occupied low flat plains between river channels. Revision of ferns, described as Acanthopteris gothanii Sze from China, shows, that these ferns belongs to Birisia alata (Prynada) Samylina. The name Acanthopteris Sze should be abandoned, due to absence of spore-bearing pinnules and poor preservation of sterile pinnules in type specimens. Based on Chinese and Russian material of good preservation, we provide emended diagnoses of the genus Birisia Samylina and its type species B. alata. Re-examination of various species of the genus Birisia revealed that this genus was widely distributed in the Cretaceous floras (from the Barremian to the Coniacian) of Eastern Siberia, New Siberian Islands, North-East and Far East of Russia, China, Japan, Alaska and Western Canada. B. alata is the most widespread species.

The Chingandzha flora comes from the volcanic-sedimentary deposits of the Chingandzha Formation (the Okhotsk-Chukotka volcanic belt, North-East of Russia). The main localities of the Chingandzha flora are situated in the Omsukchan district of the Magadan Region: on the Tap River (basin of the middle course of the Viliga River), on the Kananyga River, near the mouth of the Rond Creek, and in the middle reaches of the Chingandzha River (basin of the Tumany River). The Chingandzha flora includes 23 genera and 33 species. Two new species (Taxodium viligense Golovn. and Cupressinocladus shelikhovii Golovn.) are described, and two new combinations (Arctopteris ochotica (Samyl.) Golovn. and Dalembia kryshtofovichii (Samyl.) Golovn.) are created. The Chingandzha flora consists of liverworts, horsetails, ferns, seed ferns, ginkgoaleans, conifers, and angiosperms. The main genera are Arctop teris, Osmunda, Coniopteris, Cladophlebis, Ginkgo, Sagenoptepis, Sequoia, Taxodium, Metasequoia, Cupressinocladus, Protophyllocladus, Pseudoprotophyllum, Trochodendroides, Dalembia, Menispermites, Araliaephyllum, Quereuxia. The Chingandzha flora is distinct from other floras of the Okhotsk-Chukotka volcanic belt (OCVB) in predominance of flowering plants and in absence of the Early Cretaceous relicts such as Podozamites, Phoenicopsis and cycadophytes. According to its systematic composition and palaeoecological features, the Chingandzha flora is similar to the Coniacian Kaivayam and Tylpegyrgynay floras of the North-East of Russia, which were distributed at coastal lowlands east of the mountain ridges of the OCVB. Therefore, the age of the Chingandzha flora is determined as the Coniacian. This flora is assigned to the Kaivayam phase of the flora evolution and to the Anadyr Province of the Siberian-Canadian floristic realm. The Chingandzha flora is correlated with the Coniacian Aleeky flora from the Viliga-Tumany interfluve area and with other Coniacian floras of the OCVB: the Chaun flora of the Central Chukotka, the Kholchan flora of the Magadan Region and the Ul’ya flora of the Ul’ya Depression.

The advantages and disadvantages of a number of specialized computer programs for obtaining dimensional characteristics of biological objects by analysis of their digital images are considered in comparative terms. The authorial methodology of using a vector graphics editor Inkscape and a new online service SVGm (Scalable Vector Graphics measurer, https://svgm.cf) is proposed to measure the linear parameters of the objects in the images and to prepare the quantitative characteristics of objects and their different qualitative characteristics for the subsequent statistical analysis. An algorithm for working with Inkscape editor and SVGm online service is described in detail. Object images imported into Inkscape editor are measured using vector elements (lines, rectangles, circles, ellipses, polygons) and saved in the standard SVG format. Properties of vector figures of SVG files are converted by the online service SVGm in the measurement results shown in the table. The potential of the method is shown by the example of morphological measurements of various botanical objects.