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Aims To develop the first comprehensive syntaxonomic classification for patchy montane mire and spring vegetation across the Irano-Turanian phytogeographical region in Iran, Tajikistan and Kyrgyzstan and to explore the effects of the main environmental and geographic gradients on their distribution. Location Alborz Mountain range (Iran), Pamir-Alai Mountains (Tajikistan) and Tian Shan Mountains (Kyrgyzstan); total area about 3,000,000 km(2). Methods A database of 1,015 vegetation releves including a total of 675 vascular and bryophyte taxa was established, covering the large mountains ranges of the Irano-Turanian regions in Iran, Tajikistan and Kyrgyzstan, at altitudes ranging from 1,300 to 4,505 m a.s.l. A semi-supervised k-means analysis was performed. Additional analyses were carried out to show differences among predefined vegetation groups in terms of phytogeographical, climatic and compositional factors. Results Two large groups of mire communities, referable to mires and springs were identified. Twenty associations, one subassociation and four alliances of these wetlands, belonging to three orders and three classes, were defined. Among them, ten associations, one subassociation and two alliances were formally described as new syntaxa. Moreover, a new order Caricetalia orbicularis, that comprises phytogeographically unique vegetation of the Irano-Turanian mires, is proposed. Conclusions Based on our results and comparison between the Irano-Turanian and other phytogeographical regions, we propose a first comprehensive syntaxonomic synopsis for the Irano-Turanian mires and springs. Despite some identical character species and their vicariant nature, the Irano-Turanian, Euro-Siberian and Mediterranean mires and springs show considerable compositional differences. Irano-Turanian wetlands contain a large and distinct set of endemic plant species, which are mixed with Euro-Siberian species in the west and north, but predominate in the eastern locations. They have a patchy pattern and scattered distribution and serve as inland hotspots of wetland vegetation in the vast dry landscape of southwest and Central Asia.
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