Taxonomic inventory and distributions of Chenopodiaceae (Amaranthaceae s.l.) in Orenburg Region, Russia

Orenburg Region is located in the South Urals, mostly in the steppe zone and is characterised by various landscapes suitable for many Chenopodiaceae. The species of Chenopodiaceae are present in all major plant communities (saline vegetation, steppes, on limestone, chalk and sand, and as degraded or ruderal communities). In the steppe zone, many native subshrubby species ( Atriplex cana , Caroxylon laricinum , Suaeda physophora ) playing a crucial role in semi-deserts (known as southern steppes in the recent Russian literature) located southwards of Orenburg Region are locally found, and several annuals ( Salicornia perennans , Suaeda spp.) are most common dominants in plant communities. Some typical semi-desert species ( Kalidium foliatum , Bassia hyssopifolia , Soda foliosa , Spirobassia hirsuta ) are found in the easternmost part of the region. We compiled a checklist of Chenopodiaceae in Orenburg Region, with two new records ( Chenopodium virgatum , Corispermum laxiflorum ), based on our critical revision, comprehensive inventory of herbarium specimens and documented observations and field research. In total, we report 76 species in the Region, which is the third-highest number of the Chenopodiaceae species compared with other administrative territories of European Russia, North Caucasus and West Siberia. Alien and native taxa are distinguished. Zonal patterns of species distributions are confirmed. A preliminary conservation status is proposed for each native species. Three species are recommended for exclusion from the Red Data Book of Orenburg Region: Petrosimonia triandra (because of its extensive distribution), Kalidium foliatum and Anabasis salsa (because of the lack of actual threat to their populations). Arthrophytum lehmannianum and Salsola rosacea are considered threatened (Vulnerable) because of their restricted occurrence and population size and because their localities are under anthropogenic pressure. Atriplex hortensis , Atriplex rosea , Chenopodium acuminatum , C. karoi , C. praetericola , C. vulvaria , Climacoptera affinis , C. crassa , Halimocnemis karelinii , Salsola paulsenii and Xylosalsola arbuscula are excluded from the checklist, based on various reasons as discussed in the paper. Point distribution maps are provided for each species. Agriophyllum pungens (Vahl) Link is accepted as the correct authorship instead of "M.Bieb. ex C.A.Mey."