Studying the species distribution of rhubarbs (Rheum L.) in Kazakhstan

Critical processing of herbarium materials revealed the distribution in Kazakhstan of 10 species of the genus Rheum, including Rheum compactum L., R. wittrokii Lundstr., which are classified as rare and declining in number. R. altaicum Losinsk. was discovered – relict and endemic of Altai. To clarify the distribution in Kazakhstan and compile a summary of species of the genus Rheum, 143 herbarium sheets (1840 – 2024) from the Altai Botanical Garden (ABG), Institute of Botany (AA), and the digital herbarium of Moscow State University (MW) were reviewed and processed. 253 actual places of growth were identified for 10 species of rhubarb from the flora of Kazakhstan, belonging to 5 sections: Rhapontica A. Los., Deserticola Maxim., Orbicularia A. Los., Spiciformia A. Los., Ribesiformia A. Los. A high species diversity of rhubarb was established in the Dzungarian Alatau, Altai, Tarbagatai and Ile Kungei Alatau. Geographically, the most widespread are R. tataricum, R. nanum and R. wittrockii. The research made it possible to systematize, clarify and supplement information on the species diversity and distribution of the genus Rheum in the flora of Kazakhstan.