The selection and comparative study of new forms of the Red Book species checker tree mountain ash (Torminalis glaberrima (Gand.) Sennikov & Kurtto) were conducted on the basis of generalizing the literary data and expeditionary research on the natural and local gene pool of the above-mentioned plant. Information was presented about the peculiarities of the selection and valuable forms of the checker tree concerning the indices of vitality and morphology in the Central, South-Western, and Western Forest-Steppe of Ukraine. These forms appeared to be characterized by high vigour (over 30–40 cm), large size and mass of the fruits (1.7–2.4 g), their increased nutritional value, high ecological plasticity and ornamentality (crown shape, leaf colouration and shades during the growing season). Taking into consideration the ornamental characteristics, the selected forms are rather promising in landscape construction and phytodesign as complementary elements of oak-beech, oak-hornbeam and other species associations, as well as green corridors of the ecological network. This will contribute to the restoration and preservation of this rare species, thus facilitating restoration, spreading and conservation of this rare species, thereby increasing the stability of ecosystem components, squares, alleys, nature-conservation territories and enhancing the aesthetic qualities of the gardens when establishing harmonious landscape compositions. The fruits of T. glaberrima are characterized as raw material for processing and manufacturing of medicinal preparations and food products. The biochemical analysis of the checker tree mountain ash berries has shown that they are characterized by high content of a number of biologically active substances: polyphenolic compounds, flavonoids, vitamin С. The wide use of the checker tree will enable the food and pharmaceutical markets to be supplied with medicinal and fruit raw material by its introduction into new cultivation conditions, namely: into industrial and ornamental horticulture, forestry. The new genotypes of T. glaberrima were selected and are planned to be transferred to the National Centre for the Plant Genetic Resources of Ukraine. That will make it possible to replenish the genetic bank of Ukraine with representatives of the species, which are promising in fruit growing and ornamental horticulture, forestry and nature conservation.

The analysis of literature data allowed to highlight the importance of the plant Prunus spinosa L. as a valuable source material in the selection of stone crops and its fruits as raw materials for the food and pharmaceutical industries. Leading scientists have obtained a significant number of valuable forms and varieties of terrain, in particular in Ukraine created a variety Donets’kyy krupnyy, in the CIS such varieties as Desertnyy, Velykoplidnyy, Sverkhobilnyy, Sladkiy and others. The analysis of theoretical bases revealed that it is important in the selection of Prunus spinosa L. to involve wild species and forms with different ploidy, in particular the use of hexaploid Prunus spinosa L. avoids the stage of pentaploid hybrids in F1. It is noted that fruit juice called blackthorn or sloe is effective for the prevention of intestinal parasites, dysentery, nonspecific colitis, food poisoning, and also has antiviral and antibacterial properties, which is relevant during pandemics. Original data on the results of expeditionary research of the staff of the Institute of Horticulture of NAAS, conducted in the ecosystems of Polissya and Forest-Steppe of Ukraine are highlighted. It is shown that as a result of analytical selection and fruitful cooperation with amateur gardeners, valuable source material of Prunus spinosa L. was selected and studied. Selected clones of Prunus spinosa L. were introduced to the hospital of the Institute of Horticulture of NAAS, where during 2017-2021 it was studied by morphological features and biological properties. It was found that the forms selected in the conditions of Polissya and Northern Forest-Steppe are characterized by tallness (over 2.5 m), resistance to low negative temperatures, large-fruitedness and increased fruit weight (Nosivs’ky 1-17, Nosivsk’y 2-17, Horokhivs’ky 1-20). Forms selected in the conditions of both Western and Eastern Forest-Steppe of Ukraine are characterized by short stature (height up to 1.6 m), absence of thorns, resistance to moisture deficiency in spring and summer, yield and excellent taste and aroma of fruits (Brodivs’ky 17-19, Mukshans’ky 2-14, Poltava late, Halyts’ky 07-21, Poltavs’ky 2-17). Abundant fruiting of new forms of Prunus spinosa L. in 2021 allowed to harvest fruit from them and evaluate the morphological characteristics and biochemical parameters. The obtained data allowed to single out the most valuable in terms of fruit quality and suitability for food production.