The reproductive characteristics and invasive potential of Pseudotsuga menziesii (Mirb.) Franco and its forms in the Volgograd region have been objects to our research. Our study has shown that, in terms of its ability to spread spontaneously, P. menziesii belongs to the species that spread vegetatively or by self-seeding alone, and therefore cannot be considered an invasive species. Representatives of the genus Pseudotsuga Carr. are used in forest reclamation to fix and afforestate sands and washouts and in greenery plantings in the Lower Volga region, but have not become widespread as forest-forming species. The use of P. menziesii and its forms in protective afforestation and landscaping as fast-growing, highly decorative, long-lived trees can be aimed at solving the urgent problem of forest reclamation in degraded areas.

The place of the term «xenophyte» in the system of alien (аdventive) plants is discussed. Attention is drawn to the use of this term by botanists in three different meanings: 1) referring to unintentionally introduced plants; 2) to denominate plants introduced into the study area from other areas not having direct contacts with it; 3) to indicate pants, introduced into the study area from both remote and contact geographical areas. It is shown that the third point of view seems to be more correct. Taken into account in an expanded interpretation, this term is more relevant than any other referring to alien plants. To name a group of unintentionally introduced plants, the term «aboiletophyte» can be recommended.

Among herbaceous ergasiophygophytes of the Donetsk Botanical Garden, 21 species show high adaptive potential and are classified by us as potential dangerous invasive ones. Petrosedum reflexum (L.) Grulich, Solidago canadensis L., Arrhenaterum elatius (L.) J. Presl & C. Presl are of the greatest danger as they are likely to have «transformer» status soon, if not regulated in their distribution. The species confinement with habitats types according to their degree of naturalness, type of maintenance, luminance and development of soil cover was analyzed.

According to the Convention on Biological Diversity, it is necessary not only to protect the native flora, but also to prevent the settlement of alien species. This is especially important for specially protected natural areas. The Polistovo-Lovat bog system, the largest in the European part of Russia, is protected by two reserves – Polistovsky in the Pskov region and Rdeisky in Novgorod. The author of the article has been monitoring the introduction of alien species in both territories for more than 20 years. By now three species of invasive plants have been noted in the Polistovsky Reserve: Impatiens glandulifera Royle, Epilobium adenocaulon Hausskn., Erigeron canadensis Michx., and 12 species in the territory of its protected area. Amelanchier spicata (Lam.) C. Koch, E. adenocaulon were recorded in the territory of the Rdeisky reserve and 4 species – in its protected area. The most widely distributed are I. glandulifera, E. adenocaulon, E. canadensis. Heraculum sosnowskyi Manden. grows near protected areas.

The vast majority of alien plant species are cultivated in botanical gardens. Many of them have been assigned the status of invasive activity. One of the transformer species in the list of invasive plants of the Botanical Garden of Vyatka State University is Petasites hybridus (L.) Gaertn., B. Mey. & Scherb. Active dispersal of the species is caused by the peculiarities of its structural organization. It was established that P. hybridus is a summer-green vegetative-mobile short-rhizomes herbaceous polycarpic herbaceous polycarpic, geophyte. Due to the development of geophilic shoots, P. hybridus actively colonizes neighboring territories, and the system of shortened sympodially growing rhizomes contributes to the consolidation and retention of the developed area. We recommend to control the process of dispersal by removing a number of clones from the territory in the fall or by installing artificial fences to a depth of up to 30 cm.

One of the most important tasks in the field of biodiversity conservation is the globally recognized control of invasive species. These include alien species that occur outside their historical natural range and, when introduced, cause ecological, social or economic damage. Therefore, the problem of introducing alien species into the natural habitat of native vegetation is relevant. In the territory of southeastern and southern Kazakhstan locations of two particularly active invasive species were found: Heracleum sosnowskyi Manden. and Echinocystis lobata (Michx.) Torr. & A. Gray, capable of forming extensive thickets. Early detection and traceability of invasive species is critical to prevent their spread and reduce their damage.

An analysis of the results of floristic studies of natural and semi-natural habitats conducted from 2012 to 2023 in the cities of the southern half of Udmurtia – Votkinsk, Mozhga and Kambarka is given. The combined partial flora of natural and semi-natural habitats in the studied cities includes 819 plant species from 104 families, of which 114 species (14 %) are alien. Most of the identified species belong to the group of annual herbaceous plants, that is characteristic of alien fractions of floras. There are only 20 species which belong to tree and shrub life forms, all of them being ergasiophyphytes. When alien plants of natural habitats are distributed according to the degree of naturalization, a high proportion of epecophytes and agriophytes is observed.

The mining and technical recultivation of technozems contributes to the restoration of the numerical composition of the community of soil microorganisms that take part in the processes of nitrogen compounds transformation. This is evidenced by the restoration of the number of organotrophic bacteria of the nitrogen cycle to 0.3 million CFU/g of soil and a 2–3 times increase in the number of streptomycetes in the surface layers. The increasing indicators of microbiological transformation and mineralization of organic compounds in technozems confirm the restoration of their biogenicity during recultivation, which contributes to the intensification of mineralization processes and the absorption of nitrogen compounds by plants in the soil.

The collection-show garden «Shadow Garden» of the N.V. Tsitsin Main Botanical Garden of the Russian Academy of Sciences is one of the oldest collections of representatives of the herbaceous tier of such type of vegetation as broad-leaved forests of the temperate zone of the Northern Hemisphere. The following methods of introduction have been the basis of selection since 1973 and up to the present time: ecologicalgeographical, phytocenotic, as well as differential botanical-geographical. According to the inventory of 2024, the collection-show garden «Shadow Garden» has 351 species and 47 cultivars of shade-tolerant and shade perennial herbaceous plants. Most of the taxa presented at the exposition can be classified as promising (55 %), 38 % are very promising species and cultivars for cultivation in the middle zone, we recommend them for mass urban landscaping.

Every year, new zoned varieties appear that meet the natural and climatic conditions of a particular region. Due to the fact that most varieties of irises are bred in countries with a warm climate, there is a need to create domestic varieties that are not inferior in decorative qualities to the latest varieties of foreign breeding. As part of the study, a comparative study of Iris ×hybrida hort varieties was conducted according to such traits as resistance to diseases and pests, abundance of flowering, pollen fertility, plant height, number of flowers on the peduncle, length and width of the flower. The Gold of Canada is used as a standard variety. According to the results of our study, the varieties with the highest breeding index reflecting the presence of all the studied characteristics were identified.