Modern collections of flower-ornamental crops of the Nikitsky Botanical Gardens (NBG) are formed as a result of long-term introduction and breeding researches begun, respectively, for Rosa L. in 1812 and 1824., for Syringa L. in 1813 and 1941, for Iris × hybrida hort. in 1812 and 1986, for Hemerocallis × hybrida hort. In 1812 and 1995, for Clematis L. in 1817 and 1953, for Tulipa L. in 1812 and 1960, for Canna × hybrida hort. In 1812 and 1948, for Chrysanthemum × morifolium Ramat. in 1812 and 1939. Each collection currently includes cultivars of both foreign and domestic selection, including those created in the NBG. The total amount of the collections is 2406 species, cultivars and forms. The collections of roses, clematises, cannas and chrysanthemums are the largest in the Russian Federation. The Rosa collection includes 35 garden groups from 36 existing ones, Syringa – 6 from 7 groups of flower coloring, Iris – all 6 existing garden groups, Clematis – 14 garden groups, Tulipa – 14 garden classes from 15, Canna – both existing garden groups, Chrysanthemum – all 11 classes of this crop. Thus, the formed collections quite fully reflect the created varietal diversity of each of these crops and provide a full material for further breeding and identification of adapted assortment for landscaping in the South of Russia.

Argyranthemum frutescens (L.) Sch.Bip. (clade Magnoliophyta, class Magnoliopsida, order Asterales, family Asteraceae, genus Argyranthemum Webb ex Sch. Bip) is commonly named Paris daisy, marguerite or marguerite daisy. The species was formerly considered part of the genus Chrysanthemum, but now it is placed in an independent genus – Argyranthemum, which includes 23 species. The research was carried out in the greenhouse and on the experimental site of the Floriculture Laboratory of the “Alexandru Ciubotaru” National Botanical Garden (Institute). The article presents the results of studying the ontogenetic stages and biological characteristics of various cultivars of Argyranthemum frutescens L. Eight cultivars of Argyranthemum frutescens L. served as research subjects (White Swan, AngelicTMLemon, AngelicTMMagentа, Neptun, Pink Delight, Perfection pink, Burgundy, Giant Pink ). In accordance with the methodology, the study on cultivars was carried out taking into account the shape of the bush, the density of the foliage, the height and habit of the bush, the size and colour of the leaves, the shape, size, type and colour of inflorescences. The regenerative abilities and the capacity to produce shoots of marguerite daisy were studied. The optimal time for propagation, the length and intensity of the flowering phase of the introduced cultivars have been determined. The optimal conditions for their successful propagation and cultivation in Moldova have been established. On the basis of observations, the economic value and the best uses of marguerite daisy in landscape design have been determined. According to the results of the study on cultivars, their characteristics have been determined. It has been found that the main stages of ontogenesis in Argyranthemum frutescens L. are not clearly defined. The onset of a certain stage of development and its duration depends on climatic conditions. Some agricultural techniques for growing Argyranthemum frutescens L. under the given soil and climatic conditions have been developed.

The paper gives a brief description of the main collections and expositions of flowering ornamental plants of the Donetsk Botanical Garden. The features of plant exhibition are considered. The collections of the flowering ornamental plants of the Donetsk Botanical Garden at present include 1022 species, 1152 cultivated forms and varieties. The plant range is demonstrated according to a trend of large-scale collection plots and display gardens formation. Large-scale monoculture collections show diversity of ornamental varieties of major flowering crops. The collections of «Dahlia», «Iris», «Chrysanthemum», «Callistephus chinensis», «Paeonia», «Aster dumosum», «Canna», «Hemerocallis», «Rosa» are mostly represented by cultivars and species of the corresponding generic complexes. Those cultivars are exhibited mainly in row plantings and combined according to various characteristics, namely plant height, structure and color of the flower or inflorescence. As the cultivars of Hemerocallis × hybrida hort., Paeonia lactiflora Pall., Iris × hybrida hort., Rosa × hybrida hort. are the hardiest in steppe conditions, they are the most widely represented in flower collections. When forming thematic landscape show gardens, we were taking into account biomorphological, environmental and phytocenotic characteristics of plants. These landscaping display flowerbeds show decorative qualities of a wide range of ornamental flowers, trees and bushes with continuous flowering aspect, as well as landscaping design approaches. Over the last five years, the expositions of «Shade Garden», «E.N. Kondratyuk Garden», «Mexico» have been created and have been developing. Other exhibition areas such as «Demonstration Show Garden» and «Ground-Cover Plants» undergo extensive reconstruction. The necessity of introducing new species, intraspecific varieties and modern cultivars into the living collections is still relevant. New varieties are intensively selected: 23 cultivars bred by the Garden-based originators are now present in the collections.

Immovable objects of cultural heritage are inextricably linked to the place where they are located. The preservation of the object itself and its perception in the historical context guarantees the immutability of the protected area. Pyatigorsk historical and cultural heritage sites were used to assess the stability of their associated landscapes. The transformation of historical landscapes over time was established as a result of field research and analysis of the photo bank of data over a 125-year period. Landscape changes are associated with changes in vegetation during biological invasions, that is, they are the result of a combination of natural and anthropogenic factors. Platycladus orientalis (L.) Franco, Laburnum anagyroides Medik., Syringa vulgaris L. participate in the transformation of the landscape of the Lermontov grotto, and Robinia pseudoacacia L., Ailanthus altissima (Mill.) Swingle, and Parthenocissus quinquefolia (L.) Planch. participate in the transformation of the landscape of the Diana’s Grotto. All of them in previous years were introduced to the culture for use in landscaping Pyatigorsk. Their distribution and introduction to local cenoses began at the end of the XX century, after they entered the stage of naturalization. The listed invasive species have different geographical origins (Europe, Eas t Asia, North America) and belong to different life forms (coniferous tree, deciduous tree, deciduous shrub, deciduous liana). Platycladus orientalis (L.) Franco, Syringa vulgaris L., Ailanthus altissima (Mill.) Swingle are phytocenozotransformers, that is, they are dangerous not only for the landscapes of cultural heritage sites, but also for native plant communities. Robinia pseudoacacia L., Parthenocissus quinquefolia (L.) Planch. And Laburnum anagyroides Medik. are currently epectophytes, which does not exclude the possibility of their transition to agriophytes. The restoration of historical landscapes requires human intervention.

The article presents the results of studying the growth and development of 17 representatives of the genus Rebutia K. Schum. of Cactaceae Juss. Family (R. albipilosa F. Ritter., R. arenaceae (Cardenas) F. Ritter, R. cajasensis F. Ritter, R. donaldiana A.B. Lau & G.D. Rowley, R. flavistyla F. Ritter, R fiebrigii (Gurke) Britton & Rose ex L.H. Bailey, R. fulviseta Rausch, R. krainziana Kesselring, R. knizei (Rausch) Sida, R. kieslingii Rausch, R. marsoneri Werdermann, R. minuscula K. Schum., R. neocumingii (Backeb.) D.R. Hunt, R. pygmaea var. pectinata (Backeb.) Sida, R. senilis Backeb., R. tiraquensis Cardenas, R. xanthocarpa Backeb.) in the conditions of the Nikitsky Botanical Gardens’ greenhouse, and the influence of the microclimate on the seasonal rhythms of plant growth and development is evaluated. It is established that the studied representatives of the genus Rebutia go through all phases of seasonal development. The key values of the biological minimum of air temperatures for early - (+7,0–+8,0 °C), average (+13,0–+15,0 °C) and for late-growing (+20,0–+25,0 °C) of the species required for the onset of vegetation. The amounts of active air temperatures accumulated by the beginning of the phases of "vegetation" (from 335,2 to 1593,5 °C), "budding" (from 558,3 to 2285,0 °C), "flowering" (from 1067,8 to 2271,8 °C), "fruiting" (from 2374,8 to 3099,0 °C) are established. The following features of plant growth and development are revealed: for the transition of Rebutia species from the phenological phase "vegetation" occurring in the spring-summer period, to a state of physiological rest, which continues in the autumn-winter period, it is necessary to reduce the air temperature from +17,0–+28,0 °C to +6,0–+13,0 °C; humidity from 35,0-90,0 % to 32,0-65,0 %. Taking these measures will ensure a long and abundant flowering of Rebutia species at an air temperature from +15,0 to +40,0 °C, humidity from 43,0 to 95,0 % in a greenhouse.

The article contains the data on creating and maintaining the collections in vitro of some ornamental plants – lilac, roses, tree peonies. The analysis of morphogenetic processes during microclonal propagation of lilac cultivars demonstrates well-defined correlation between susceptibility of this culture to mineral mixture of nutrient medium and plant genotype. Rose cultivars from different garden groups keep high growth capacity during 12 subculturing cycles on Murashige Skoog medium (MS) supplemented with 0.5 mg/l BAP. For all culturing tree-peonies cultivars Woody Plant Medium (WPM) with double content of Ca2+ ions and total exception of Cl- ions turns out to be more suitable. The opportunity of 10 lilac cultivars and 4 rose cultivars preservation in slow growth cultures was appreciated. The correlation between long-term cultivation in low temperature and genotype of ornamental plants cultivars was shown. Thus, 18 ºС turns out to be suitable for creation of slow-growth collection of all studied rose cultivars, and 14 ºС – only for 'Nina Weibull'. Maintaining of lilac microshoots at 10 ºС during 5 months practically did not act negatively on their viability.

The study of phytocoenotic diversity of oak and oak-hornbeam forests of the lower part of the forest belt in the Belaya river basin (Western Caucasus) was performed using the Braun-Blanquet approach. Five floristically different groups of releves were identified based on quantitative classification (Ward's method, Jaccard Distance Measure). An association rank was established for each group. According to the results of comparative syntaxonomic analysis, three associations of moderately masic oak and oak-hornbeam forests - Geranio sanguinei-Quercetum petraeae ass. nova hoc loco (diagnostic species: Pinus sylvestris, Calamagrostis arundinacea, Rhododendron luteum, Geranium sanguineum, Vaccinium arctostaphylos), Inulo salicinae-Quercetum petraeae ass. nova hoc loco (diagnostic species: Brachypodium pinnatum, Inula salicina, Dorycnium graecum, Laser trilobum, Trifolium medium, Viola alba, Stachys officinalis, Pyrethrum poteriifolium, Phleum phleoides, Teucrium chamaedrys, Genista patula) and Acero tatarici-Carpinetum betuli ass. nova hoc loco (diagnostic species: Phalacroloma annuum, Thalictrum minus, Torilis japonica, Prunus divaricata, Physalis alkekengi, Lamium maculatum, Acer tataricum) were included in the alliance Crataego-Carpinion Passarge 1981, order Lathyro-Carpinetalia Passarge 1981, class Carpino-Fagetea Jakucs et Passarge 1968. The correct syntaxonomic position of two associations of mesic hornbeam and oak-hornbeam forests - Dryopterido filicis-maris-Carpinetum betuli ass. nova hoc loco (diagnostic species: Dryopteris filix-mas, Circaea lutetiana, Aegopodium podagraria, Paris incompleta, Abies nordmanniana, Impatiens noli-tangere, Festuca gigantean, Symphytum grandiflorum, Dipsacus pilosus, Aconitum orientale, Asperula caucasica, Moehringia trinervia, Polygonatum orientale) and Vincetoxico scandentis-Carpinetum betuli ass. nova hoc loco (diagnostic species: Viola hirta, Vincetoxicum scandens, Ligustrum vulgare, Lathyrus vernus, Polygonatum multiflorum, Rubus caucasicus, Euphorbia squamosa) has not been determined, however their relations to beech and beech-hornbeam forests of the order Rhododendro-Fagetalia orientalis Passarge 1981 were noted. The described associations of oak-hornbeam forests correspond to the regional ecological series of communities along the moisture gradient.

The realized niche of the community, which is part of the association Astragalo borysthenici-Ephedsretum Korzh. et Klyukin 1990 (union Verbascion pinnatifidi Korzh. et Klukin 1990, order Festucetalia vaginatae Soo 1957, class Festucetea vaginatae Soo 1968 em Vicherek 1972) described on a leaning dune, is discussed. Its composition is dominated by polycarpic grasses, represented by ephemerals and ephemeroids with a semi-rosette type of vegetation and a deep taproot system. An attempt has been made to predict the survival of the species found in Agropyron dasyanthum Ledeb., known as the endemic of the Lower Dnieper sands. To assess the ecological structure of the realized niche of the phytocenosis and the correspondence to it of the potential niche of fluffy flowering wheatgrass, an original program for calculating the packing density of community species on the gradients of factor-conditions and factor-resources was used: acidity of the substrate, salt regime (anionic composition), carbonate content, nitrogen content, granulometric (mechanical) composition (porosity) of the substrate). The result of the analysis was an unambiguous conclusion that Agropyron dasyanthum Ledeb. in the new conditions of the shell-detritus substrate, it ideally fit into the conditions of the climatope and, more or less, into the structure of the edaphotope. The real threat to the community is theanthropogenic impact and loss of productivity in the Sea of Azov.

The aim of this work is to assess the level of taxonomic diversity and to analyze the structure of the vascular flora of the coastal biotopes of the Southern Crimea. The work is based on the results of long standing field research, which was carried out by the traditional route-reconnaissance method, analysis of YALT herbarium materials and data from literary and Internet sources. Arealogical and biomorphological characteristics of the species are given according to "Biological Flora of Crimea" by V.N. Golubev, biotope coding – according to EUNIS habitat classification. The nomenclature of taxa corresponds to the "Spontaneuos flora of the Crimean peninsula" by A.V. Yena and international databases IPNI, Euro+Med PlantBase, The Plant List, Catalog of Life. 17 types of biotopes of the local, regional and European levels were identified in the coastal landscapes of the Southern Crimea according to the EUNIS habitat classification. An annotated list of vascular plants of coastal habitats has been compiled, which includes 334 species and subspecies from 223 genera of 58 families. The "core" of the studied flora has been identified, which includes 94 species most characteristic of it from 74 genera of 29 families. The analysis of the systematic, geographical and biomorphological structures of the flora and its sozological assessment are carried out. It has been established that the diversity of the coastal landscapes of the Southern Crimea is represented by 17 types of habitats, the flora of which includes 334 species and subspecies from 223 genera of 58 families of vascular plants. The most characteristic for the studied biotopes are 94 species from 74 genera of 29 families, which constitute the "core" of their flora. 14 coastal biotopes and 41 plant species have conservation status of different levels.

The ontogenetic states of T. biebersteiniana in the broad interpretation which grows in Transdnistria was refined. In the tract of Kalagur-Stroentsy four age states were defined, on limestone faults along the valley of the Dniester - five. A comparative study of the main demographic indicators of mesophilic and xerophilous ecological groups of T. biebersteiniana has been conducted. The morphometric indicators of the populations of both ecogroups have been identified and analyzed: total population density, ontogenetic spectrum, projective cover, and age and efficathy indices. The method of propagation of mesophilic and xerophilous ecogroups representatives has been clarified. Mesophilic plants propagated vegetatively, the forming bulbs have a sporophyte origin, and the mature mesophilic populations are renewed homophasically. Xerophilous plants reproduce mainly sexually; the reproduction of developing populations is mainly heterophasic. Both ecogroups were rejuvenated, so their resistance as the survival in phytocenosis was unified by the comparable reproduction and replacement indices. The surveyed mesophilic and xerophilous populations were classified as young, left-handed, normal, and incomplete. Populations of both ecogroups, being young, with high reproduction and replacement indices, were not affected by the tulip breaking virus, and were relatively resistant and adapted to their biotope. Prospects for their continued existence now are quite favorable in the absence of sudden and sharp effects on them of possible biotic and abiotic stressors. There is a low net reproduction in the plants of the mesophilic group in natural populations. The inducing of additional micro bulbs in the culture of in vitro based on indirect somatic embryogenesis is promising to increase T. biebersteiniana propagation rate.

The research was conducted on the basis of collection plantings of the Nikitsky Botanical Gardens - National Scientific Center (Southern Coast of the Crimea) during the summer seasons 2019-2020. Indicators of a number of parameters of the water regime of four Ficus сarica cultivars of different origin were determined, and characteristic features of each genotype were revealed under the influence of arid factors. From May to August, the indicators of leaf tissue water content of the studied genotypes decrease by an average of 8-10 %. During the period of mass fruit ripening, the loss of 10-15 % of moisture by the leaves is a sublethal water deficit for the studied objects, except for Sary Stambulsky cultivar. In the absence of fruit load, the level of permissible sublethal moisture loss increases to 15-20 %, and in 'Sary Stambulsky' can reach 30 %. As a result of a comparative assessment of the complex of physiological indicators, the genotypes 'Sary Stambulsky' and 'Sabrutsia Rozovaya' are potentially adaptive and resistant to hydrothermal stress were identified. The leaves of these cultivars showed a high ability to retain moisture in combination with the ability to perform the most complete tissue repair after critical dehydration. During periods of increased exposure to arid factors, the loss of moisture by leaves in the first hours of wilting in these cultivars did not exceed 20 %. The minimum level of water-retaining forces, as well as in most cases, unsatisfactory turgidity was shown by plants of the Muason (Krymsky Chyorniy) cultivar. Depending on the weather conditions of the summer months, the degree of dehydration of leaf tissues of this genotype after 2 hours of wilting varied in the range of 8-25 %, which indicated a low stability of the water regime. The genotype ‘Opylitel Nikitsky’ was characterized by an average level of drought tolerance.