A NEW FORM OF Spiraea flexuosa FROM WESTERN SAYAN

The issues of studying biological diversity, including at the intraspecific level, are among the most important in biology. The form diversity of woody plants is far from fully revealed. Most often, new forms are identified by crown habit, size and shape of leaf blades and their pubescence, size and color of flowers. Much less attention is paid to the color of the leaves. In the course of fieldwork in 2021, on the Kurtushibinsky Ridge, which is part of the Western Sayan system, in the protected zone of the Sayano-Shushensky State Natural Biosphere Reserve near the village of Bazaga, the authors found a small population of spiraea flexuous ( Spiraea flexuosa Fisch ex Cambess.) with bright, carmine-red leaves. Previously, no forms were noted in spiraea flexuous. However, for the closely related species S. сhamaedryfolia , which some authors previously considered a synonym for spiraea flexuous, 3 forms were described: f. crataegifolia Zhl., f. transiens Zhl. and f. stenophylla Zhl. They differed only in the shape and size of the leaf blades. Forms with leaves other than typical green have not been described before. The found form, being introduced into the arboretum of the Central Siberian Botanical Garden of the Siberian Branch of the Russian Academy of Sciences, retained its characteristics. In accordance with the Code of Botanical Nomenclature, she was given the name - Spiraea flexuosa Fisch ex Cambess., f. atropurpurea Karakulov et Shaulo. The red-leaved form of spiraea flexuousis highly decorative and can be successfully used in landscaping settlements in Siberia.