Assessment of the Potential Risk of Poisonous Plants in Rostov-on-Don

Introduction. The flora of most urban areas has received scant attention regarding toxicity, resulting in the potential for humans and animals to encounter poisonous plants. Furthermore, there is an influx of new potentially hazardous species into populated areas. It is evident that there are two primary mechanisms through which their propagation occurs. The first of these is natural population increase. The second is the introduction of ornamental species in landscape projects. The presence of poisonous plants in urban areas is frequently identified solely on the basis of symptoms including poisoning, dermal and eye burns. Children are the most vulnerable in this regard. The situation in Russia has been examined using the example of several urban ecosystems; however, the distribution of toxic flora in Rostov-on-Don remains unstudied. The aim of this research is to evaluate the potential hazard posed by poisonous plants in Rostov-on-Don. Materials and Methods. The research focused on species of poisonous vascular plants growing within the city limits of Rostov-on-Don. The data was collected during fieldwork in 2023–2024 using the route method. Information on the presence of poisonous plants on the territory of the city in 2007–2022 was also taken into account. The names of the plant species are given according to the Plant List database. The toxicity class was determined according to the A. Filmer scale. Results. In the urban context of Rostov-on-Don, a total of 66 species of poisonous plants were identified (8% of the city's total floral biodiversity). They belonged to diverse hazard categories according to their potential impact on human and animal health. A thorough analysis of taxonomic structure of the toxic flora revealed the most prominent orders: Ranunculales (14 species) and Solanales (6 species). The potentially lethal plants within the city limits included Hyoscyamus niger, Conium maculatum, Aristolochia clematitis, Convallaria majalis, Ricinus communis, and others (21 species). The ecological and cenotic analysis demonstrated that almost one third of the detected toxic plant species (30%) were associated with ruderal habitats, i.e. roadsides and abandoned areas. The majority of species (41%) were found to be associated with artificial phytocenoses that were created for ornamentation. Of particular concern were plants bearing poisonous fruits of high ornamental value. This group comprised 14 species, including Parthenocissus sp., Phytolacca americana, and Wisteria sinensis. A biomorphological analysis of the toxic flora revealed the predominance of perennial and annual grasses (66%). Shrubbery, conversely, exhibited a lower level of diversity (16%), yet demonstrated a more extensive geographical distribution. Discussion and Conclusions. This is the first study to assess the potential threat posed by poisonous plants in urban ecosystems within the southern Russian region. The identification of toxic plant species, their role in the urban landscape and ways of their further development will help to minimize poisoning by poisonous plants. Uncontrollably spreading ruderal toxic plants, among which particularly dangerous species have been found, require special attention. During landscaping and green construction, the toxicity of each specimen should be taken into account.