Vol 109, No 9 (2024)

The vegetation of swampy lakes in the Caucasus is considered using the example of Khmelevsky lakes, located on the territory of the Sochi National Park (Krasnodar Territory). On Khmelevsky lakes, different stages of mire formation are observed, from open lakes to mires originated from completely overgrown lakes. Five associations of mire vegetation and one of coastal-aquatic vegetation were identified. The communities of these associations form the following belts on overgrowing lakes: a swampy mineral shore covered with communities of ass. Cariceto rostratae-Sphagnetum jensenii, Cariceto rostratae-Warnstorfietum fluitantis, Junceto-Polytrichetum communae; watered sites occupied by thickets of ground-rooted sedges (ass. Caricetum rostratae) or covered with sedge-sphagnum floating mats formed by communities of ass. Cariceto rostratae-Sphagnetum jensenii or Cariceto rostratae-Sphagnetum flexuosi; open water, in some places with coastal-aquatic communities ass. Eleocharitetum austriacae. For the first time in the Caucasus, communities with the moss cover dominated by Sphagnum jensenii and species of the genus Polytrichum have been described. Based on research materials by V.V. Akatov (1987) and satellite images, the dynamics of stabilization of floating mat on one of the lakes and overgrowing of another lake were traced. A strong negative impact of grazing was noted.

Helianthus occidentalis is poorly studied embryologically, but it may be very useful in breeding due to its high resistance to pests and diseases. Significant variation in the viability and size of pollen grains in the samples of different origin is characteristic for this species. No essential deviations in the anther development were noticed before microsporogenesis start. Further, the following anomalies were found: late chromosomes outside of the spindle; dyads with one nucleus being degenerating on anaphase I; formation of micro- and macronuclei during the second division of meiosis; degeneration of several nuclei within a tetrad; formation of triads, dyads and monads of microspores instead of tetrads. We have noticed significant heterogeneity of pollen grains by size. Deformed and compressed ones were noticed, as well as those with the structure of dyad or tetrad of cells within their wall. There is some data in literature on similar anomalies both in plants of other taxa and in Helianthus plants, mainly of the hybrid origin. One of the supposed reasons of the multiple anomalies in development and deterioration of pollen quality in the sample of H. occidentalis under investigation is a possible introgression of chromosomes from one of closely related diploid species as a result of hybridization that took place in the natural population. The conducted study once again confirms the need for cytological analysis to identify potential pollinating plants for sunflower breeding.

Calicium notarisii and Cladonia humilis are reported as new to the lichen flora of Dagestan. Herewith the species C. humilis was not known before in the Caucasus. Descriptions of the specimens with information of their habitats, distribution and some notes are given. Morphological and chemical distinctions between C. humilis and similar species are discussed.

St. Petersburg is the largest city in the world north of 60° N. Urban areas neighbor on relatively undisturbed sites with natural south taiga landscapes (about 30% of the city area). The conventionally primary vegetation is represented by spruce, pine and black alder forests, different types of bogs, maritime meadows, coastal-aquatic vegetation. Secondary vegetation includes small-leaved forests and upland meadows.

For many years, comprehensive environmental surveys of the city territories have been carried out in St. Petersburg in order to justify the feasibility of creating natural protected areas there. Currently, there are 17 protected areas of regional status in St. Petersburg with a total area of 92 km². Another 17 territories (about 70 km²) have been surveyed and recognized as having a high conservation value. One of the tasks of geobotanical research is to identify plant communities rare in the city and needing protection. The existence of these communities is due to a number of factors related to the geographical location and history of the city’s development. The conservation value of communities The communities conservation value is based on their rarity and is determined by a number of criteria. Based on these criteria, four categories are proposed: floristic (dominance of a rare species), structural (combinations of structural components formed by species with contrasting ecological-coenotic characteristics), ecotopic (presence of rare ecotopic conditions), rare communities (encountered 1 to 3 times over the entire research).

Totally, more than twenty types of rare communities have been identified. The first category includes communities with the species listed in the Red Book of St. Petersburg – Myrica gale, Viola uliginosa and Euphorbia palustris. The second category includes forest communities of Kotlin Island with structural features of the lower layers. The third, largest category includes small-leaved nemoral forb forests, maritime meadows, extrazonal broad-leaved forests and hazel bushes. Their existence is determined by rare ecotopic conditions, which depend on the coastal position and geological and geomorphological features of the city. The fourth category includes old-growth spruce forests, plant communities with rare species Equisetum hiemale and Carex brizoides, and unique for the city ridge-hollow-lake complex on the Sestroretskoye bog.

The location within the city, characteristic habitats and dominants of the layers are described for each community. For many types of communities, tables with relevés are provided.

The article presents two little-known facts from the biography of the outstanding botanist Ivan V. Palibin: his entry, self-taught, into the milieu of professional botanists and his long-term co-operation with the Troitskosavsk-Kyakhta Branch (TKB) of the Imperial Russian Geographical Society (IRGS). In both cases, the driving motive behind his actions was a selfless love of botany and an early interest in the flora of the East Asian region, be it Transbaikalia, the Russian Far East, or northern Mongolia and Korea. The primary sources for the work were documents from St. Petersburg and Moscow archives and materials from the Proceedings of the TKB. He worked on a pro bono basis in the Herbarium of the Moscow University and the Herbarium of the Imperial Botanical Garden in St. Petersburg. In 1898 he became a member of the IRGS, which sent him to eastern Mongolia in 1899 for geographical and natural history research. During the trip the scientist established scientific contacts with the leadership of the Troitskosavsk-Kyakhta branch of the IRGS. At the request of the chairman of the department Y.D. Talko-Gryntsevich, Palibin identified plant species collected by local collectors and assisted in the preparation for publication of the department's scientific papers.