Abstract: Firozeh watershed with an area of 270 km2 is located in 20 km South of Bojnord (North Khorasan province). The altitude of the area ranges is 1280 to 3010 m. The mean annual rainfall is 385.7 mm and the mean annual temperature is 8.9 C. In order to floristic study in this watershed, plant samples were collected during six growing seasons (2003-2008) and identified using different flora references. The life forms were determined and the biological spectrum of the area was plotted. The position of the area related to phytogeographical classification was investigated based on geographical data and references. In this research 56 family, 243 genera and 405 species were identified. The largest families of region are: Compositae with 52 species and poaceae with 47 species. Hemicryptophyte with 149 species are the most frequent life forms in the area. The distribution of the 262 species is restricted to Irano- Turanian region. Of these, 47 species are endemic of Iran. Furthermore, according to the IUCN, three categories of plant species so called vulnerable, lower risk and data deficient are determined. There are, in total, 60 threatened plant species in this area.

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