A check-list of endemic vascular plants of the Tian-Shan Mountains, including plant distribution along mountain ranges and in Central Asian countries, has been compiled for the first time in this study. The list of Tian-Shan flora consists of 871 endemic species and subspecies. One subspecies belongs to Pinaceae (Pinopsida) and 870 taxa belong to Magnoliidae (dicots, 732 taxa, and monocots, 138 taxa). The endemic flora belongs to 39 families and 187 genera. The largest number of endemics is concentrated in the mountain ranges of Kyrgyzstan (225 national endemics, 507 taxa in total) and Kazakhstan (205 national endemics, 485 taxa in total). Uzbekistan occupies the third position (69 national endemics, 320 taxa in total). Tajikistan has fewer endemics: 82 taxa, of which only 16 taxa are national endemics. The most represented families and genera are: Asteraceae, Fabaceae, Apiaceae, Lamiaceae, and Amaryllidaceae; and Astragalus, Allium, Cousinia, Oxytropis, and Gagea, respectively.

Constituting one of Earth’s major biomes, steppes are characterised by naturally treeless extra-tropical vegetation. The formation of the Eurasian steppe belt, the largest steppe region in the world, began in Central Asia during the Neogene. In the glacial stages of the Pleistocene, steppe displaced forest vegetation, which in turn recolonised the area during the warmer interglacial periods, thus affecting the distribution of plants adapted to these habitats. Krascheninnikovia ceratoides (Chenopodiaceae) is a plant characteristic of dry steppe and semi-desert formations. Earlier studies showed that the ancestor of this autochthonous steppe element originated in Central Asia during the Miocene/Pliocene, i.e., in the same region and at the same time as the first appearance of steppe vegetation. However, as the extant lineages of Krascheninnikovia ceratoides diversified only 2.2 ± 0.9 Mya, it may represent a modern element of current dry steppe and semi-desert formations, rather than a component of the first steppe precursors of the Miocene. As such, it may have capitalised on the climatic conditions of the cold stages of the Quaternary to expand its range and colonise suitable habitats outside of its area of origin. To test this hypothesis, phylogeographic methods were applied to high-resolution genotyping-by-sequencing data. Our results indicate that Krascheninnikovia originated in western Central Asia and the Russian Altai, then spread to Europe in the West, and reached North America in the East. The populations of eastern Central Asia and North America belong to the same clade and are genetically clearly distinct from the Euro-Siberian populations. Among the populations west of the Altai Mountains, the European populations are genetically distinct from all others, which could be the result of the separation of populations east and west of the Urals caused by the Pleistocene transgressions of the Caspian Sea.

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Allium toksanbaicum from South East Kazakhstan is described as a new species. Molecular markers reveal a close relationship to A. obliquum and some other central Asian species of the section Oreiprason. We investigated the phylogenetic relationship of the new species based on sequences of two chloroplast spacers (rpl32-trnL and trnQ-rps16) and the nuclear ribosomal DNA internal transcribed spacer (ITS) region. The new species is diploid with a chromosome number of 2n = 2x = 16. A detailed morphological description, illustrations and karyotype features of the new species are given. With its falcate leaves, the new species is very similar to A. carolinianum from the section Falcatifolia, but in the shape of the inflorescence and flowers it is very different from it. From A. obliquum it differs for the purple colour of flowers and filaments, as well as the presence of teeth at the base of inner stamens.

Polymorph Allium pallasii s.l. from monotypic A. sect. Pallasia was studied using a wide spectrum of methods and divided into two clearly morphologically, geographically, cytologically and genetically isolated species: A. pallasii s. str.—North-East Kazakhstan, Western Siberia, and the Altai Mountains; A. caricifolium—Kyrgyzstan, Northwest China, South-East Kazakhstan until Zaysan Lake in the east. Despite serious genetic differences, both species are sisters and are related to species of the A. sect. Codonoprasum (Subg. Allium). Allium caricifolium differs from A. pallasii s. str. by taller stems, dense inflorescence, and with filaments longer than perianth. The possible phylogenetic reasons for the separation of these species are discussed. A nomenclature analysis of synonyms was carried out.