Khorassan- Kopet Dagh (KK) floristic province (NE Iran and S Turkmenistan) is a transition zone and a corridor connecting different provinces of the Irano-Turanian region and Hyrcanian montane forests of the Euro-Siberian region. The climate of the area is distinctly continental and drier than the nearest mountainous areas, however, a unique combination of Irano-Turanian species and presence of a local center of endemism have shaped a very diverse and unique flora in the area. Based on current data, the flora of the KK comprises about 2600 species, almost one-third of the flora of Iran, 550 species out of which are endemic or sub-endemic to the area. The complicated topography, high habitat heterogeneity, and long vegetation history have permitted the formation of diverse community types in the area. Most of the KK endemic species occur in montane steppe communities on the middle mountain belt to the subalpine zone, however, a considerable number of endemic and sub-endemic plants belong to the unique lowland habitats such as calcareous, serpentine and gypsum ecosystems. Based on a preliminary checklist of edaphic plants in KK, about twenty percent of endemics are restricted to these types of soils. In this presentation, I describe the diversity, distribution patterns, biodiversity hotspots and conservation status of the edaphic endemic plants in KK with special reference to the current data on gypsum substrates in the area.

Keywords