This study examines the characteristics of vegetation in the semi-arid regions of Southern Siberia (Southeast Altai, South-Western and Southern Tuva, and the southern areas of Transbaikalia and Dauria). Extreme temperature conditions (average January temperature: –25 to –30 °С, average July temperature: +25 to +30 °С) and low precipitation (100–150 mm) falling in the second half of summer are considered to be the specific feature of the semi-arid climate. The vegetation of semi-arid regions consists of desertified steppes, desert steppes, semi-deserts, communities in solonchak soil type, and petrophytic communities. In the flora of the Chuya Basin, a group of species typical of desert-steppe landscapes was identified. Species were selected based on their distribution restricted to the Chuya Basin, as well as their association with desert, steppe, solonchak, and petrophytic vegetation was accepted. 115 species were identified in the flora of the Chuya Basin, which are typical for desert-steppe landscapes. The dominant families in the taxonomic spectrum include Chenopodiaceae, Asteraceae, Fabaceae, Poaceae, and Boraginaceae families, with the most prominent genera being Artemisia, Astragalus, Lappula, and Taraxacum. More than half of desert-steppe species are herbaceous perennials, quite a lot of annuals (24.8 %) and semi-shrubs (12.3 %). More than half of the species (50.4 %) are associated with communities in solonchak soil type, 37.2 % with desert-steppe species, and 12.4 % with petrophytic communities. The geographical spectrum is dominated by South Siberian-Mongolian species, with fewer Turanian-Central Asian and endemic species. Relict species from the Tertiary and Late Pleistocene of desert-steppe landscapes in the Altai Mountains were identified.