Fruits formation was ranging from 25 to 100 %. Seeds germination rate was from 7.7 up to 100 %. Most week plants were registered in the progeny of 'Darling Dilemma' × 'Fantasy Fire' (71 %) and 'Frans Halls' × 'Siloam Tee Tiny' (73 %).

The paper deals with the biological features of introduced species of Cotoneaster genus in the middle taiga subzone of the Komi Republic. The vegetation, flowering, fruiting, rhythm of shoots growth, winter resistance and seed productivity of six species of perennial plants of the genus Cotoneaster in new growth conditions were studied. The seasonal rhythm of development of all studied plant species at the point of introduction corresponds to the climatic conditions of the middle taiga subzone. The most promising species were selected for cultivation.

In the Botanical Garden of the Institute of Biology, Komi Scientific Center, Ural Branch of the Russian Academy of Sciences, a collection of plants of the genus Sorbus complex is studied. Currently it includes 23 species and more than 40 samples of different geographical origin, as well as nine varieties. The studied plants are in the pregenerative and generative periods of ontogenesis. The morphobiological features of individuals of different species of mountain ash at these stages of development were determined. Introducers of East Asian origin in the conditions of the North have time to fully complete the cycle of seasonal development and are highly winter-resistant. Plants that have entered the generative period of development form full seeds. Experiments on vegetative reproduction with the use of stimulants of root formation and without them showed a different ability of half-woody cuttings of the species and varieties of mountain ash to rooting. The most promising for further cultivation in cold climates and the selection of decorative and productive forms can be considered species of East Asian and American origin, as the most winter-hardy. Other specimens of S. mougeottii and S. austriaca (species no less interesting as ornamental and fruit plants) should be brought to the test as well as plants of these species should be grown from the seeds of local reproduction.

The paper deals with the biological features of the East Asian species of the genus Cotoneaster Medik. when introduced in the Komi Republic. The features of vegetation, the dynamics of shoot growth, as well as the specificity of growth processes in the North, the degree of winter hardiness of introduced species, flowering and fruiting of plants of three species of this genus have been studied. Long-term observations have established that the studied plants have a long seasonal rhythm of development, they are characterized by late terms of the end of the growing season. Some species in summer, due to their high ability to regenerate shoots, quickly restore the crown, which allows them to enter the flowering and fruiting phases annually under conditions of introduction. Of the seven species, three have entered the generation period, and only two differ in the regular fruit formation. Plants of C. allochrous , C. bullatus , C. roseus , and C. amoenus differ in the late start and late end of the growing season, which affect their winter hardiness. C. dammeri , C. horizontalis and C. ascendens are recommended as the most promising plants for growing in the northern region with an early start and late end of the growing season. The decorativeness of the studied dendrointroducents, which persists during the growing season, is noted.