GROUNDCOVER PLANTS OF GENERA COTONEASTER MEDIK AND SPIRAEA L. IN COLLECTION OF O. V. FOMIN BOTANICAL GARDEN, PROSPECTIVE FOR CULTIVATION IN UKRAINE

The introduction of the woody plant genera such as Cotoneaster, Crataegus, Spiraea, Rhododendron, Magnolia and others has been conducted with the help of generic complexes of F.M. Rusanov (1971) in O. V. Fomin Botanical Garden since 1965. Over the 50 year period a significant amount of introduced species were found and handed over for use in various Ukrainian industries. By the end of 2016, these families have been submitted in accordance: 200, 71, 135, 172, 72 species and intraspecies taxa. In the collection there are types, forms and varieties of Cotoneaster and Spiraea, which are still not well-known in the culture in Ukraine. The aim of our study is to identify among the variety of Cotoneaster, Spiraea plants, the collections of the Botanical Garden, which are perspective in landscape design as the new taxa for cultivation in Ukraine. In this publication we draw attention to a group of plant genera Cotoneaster, Spiraea, which have a dwarf growth and are capable to create a dense soil covering. These undemanding squat plants can cover the soil surface intensively by means of rhizomes, aboveground creeping shoots and root sprouts. Their height does not exceed 0.2-0.3 meters. The objects of the research became 13 taxa of the genus Cotoneaster (two of which are deciduous) and six varieties as well as one hybrid genus Spiraea. The study was conducted through the systematic phenological observations during 1975 and 2016. The results were processed by the statistical methods. The promising groundcover plants were 13 varieties of Cotoneaster and 7 kinds of Spiraea. Reproduction of the recommended species and cultivars is possible by seed or vegetative means. When planting the multiplication material in the vegetative way the cuttings should be provided (they are to take roots in the greenhouse conditions or in the open field first). The rooted cuttings or seedlings should be grown in the nursery for 2-3 years. The planting density should be calculated depending on the growth area of plants. The care for the groundcover plants is reduced to periodic removal of weeds, the rejuvenation of the curtain by removing old branches, watering and fertilizing of plants. These curtains are perennial, so they require minimal care during the first couple of years after planting, and further the costs of their maintenance are reduced.