Ornamental perennials in floriculture of Central Ukraine: taxonomic diversity, structural analysis, and naturalization success of alien species

This study presents a comprehensive analysis of the taxonomic diversity, acclimatization processes, and naturalization success of ornamental herbaceous perennials and semi-woody plants in Central Ukraine. The role of these plants in regional floriculture and the ecological risks associated with their introduction are discussed. It was found that regional floriculture probably has a long history, but the first specific records on the study object appeared at the end of the 18th century. The research revealed that 794 species, subspecies, and hybrids from 301 genera and 70 families are cultivated in the regional floriculture. The largest number of species and infraspecific taxa belong to the families Asteraceae (11.6 %), Asparagaceae (6.5 %), Lamiaceae (6.5 %), Ranunculaceae (6.0 %), and Crassulaceae (5.3 %). The most represented genera are Allium (25 species), Iris (19 species and hybrids), and Primula (14 species and hybrids). It was found that 84.5 % of the studied species and infraspecific taxa are ergasiophytes, while 15.5 % are native plants, often represented by cultivars, reflecting the predominance of introduced species and cultivars in the assortment of ornamental plants. Among the plants used in floriculture in Central Ukraine, herbaceous perennials species constitute the largest group (77.5 %), while the presence of semi-woody plants (5.1 %) and annual and biennial plants (17.4 %) is significantly lower. The distribution of native species by range types covers all major elements of the natural flora, but species with European (23.6 %), Eurasian (19.5 %), and European-Mediterranean (13.9 %) distribution patterns are the most frequently cultivated. Among ergasiophytes, most species and infraspecies have Asian (28.0 %), Mediterranean (19.4 %), and American (19.1 %) origin, with a significant proportion of hybrids and cultigenous species (11.2 %). Overall, species from all geographic regions, including tropical and oceanic zones, are represented in floriculture.An essential aspect of the study was assessing the acclimatization and naturalization degrees of ornamental alien plants. The scheme for overcoming limiting barriers by alien species was supplemented with a model describing the acclimatization of ergasiophytes and their escape beyond cultivated areas. The acclimatization of ergasiophytes in this study is considered a controlled process that is ongoing simultaneously with spontaneous naturalization. It was found that 44.9 % of ergasiophytes achieved complete acclimatization, 15.4 % penetrated beyond cultivation sites, becoming ergasiophygophytes, 2.7 % naturalized, and 1.5 % acquired invasive status. For example, invasive plants include Helianthus tuberosus, Reynoutria japonica, and Solidago canadensis. Potentially invasive species requiring monitoring and further study comprise Corydalis caucasica, Petrosedum orientale, Symphyotrichum × versicolor, Thladiantha dubia, and others.