New taxa of trees and shrubs (Spiraea × schinabecki, Swida rugosa, Ulmus ‘Columella’) in green spaces of St. Petersburg

St. Petersburg City is a famous world center of landscape art and applied botanical science, where, since the 18th century, a variety of introduced trees and shrubs have been used for testing and landscaping. The sources of replenishment of the assortment of trees and shrubs in the city are mainly the activities of gardening farms. Therefore, researchers constantly note new taxa for the city green spaces. As a result of research conducted in 2019–2023. in 18 parks and gardens of St. Petersburg, three new species of woody plants for the city were identified: shrubs Spiraea × schinabecki Zabel (Shinabek's spirea) and Swida rugosa (Lam.) Rydb. (= Cornus rugosa Lam., wrinkled dogwood) and the tree Ulmus ‘Columella’ (hybrid elm cultivar Columella). The purpose of the study: to confirm the status of the finds as new taxa for the green spaces of St. Petersburg and to identify their distribution and, if possible, condition in botanical collections of Russia. These taxa are still used to a limited extent in landscaping Russian cities, although one of them, Swida rugosa, began to be tested in the second half of the 19th century in St. Petersburg – in the Botanical Garden of the Komarov Botanical Institute RAS. In the conditions of St. Petersburg, these three taxa have shown sufficient stability, are in satisfactory and good condition, decorative and can be used in the future for landscaping the city. And Swida rugosa, which is found in botanical gardens in the European part of Russia and Siberia, most likely can be used more widely in landscaping the populated areas of Russia in the southern forest zone. Spiraea × schinabecki is given for only two botanical garden. And Ulmus ‘Columella’ most likely has never been grown in Russian botanical gardens. However, due to the high resistance to Dutch elm disease, it definitely deserves widespread use in green spaces in Russian cities.

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