The high-altitude Lake Neor along with its southern and southwestern marginal peatlands in northwestern Iran (Ardebil province) are unique in terms of floral and vegetation diversity. This floristic study presents the floral composition of different vegetational belts of the southern part of the lake and its marginal peatlands along a humidity gradient. Four vegetation zones were defined based on vegetation composition and water availability. A total number of 84 plant taxa belonging to 45 genera and 27 families were identified. The most abundant families included Poaceae (10 species), Cyperaceae (9 species), Asteraceae and Fabaceae (6 species each) as well as Polygonaceae and Santalaceae (4 species each). The life form analysis revealed that hydrophytes (8 species, 61%) and helophytes (10 species, 47%) predominated in the first (shallow margins of the lake) and second (lake-peatland transition) zones. Whereas hemicryptophyte was the main life form in the third (peatland) and fourth (wet meadows) vegetation belts, with 23 (70%) and 15 species (80%), respectively. From a chorological viewpoint, the vast majority of the flora under consideration belonged to pluriregional and/or Irano-Turanian origins. The Neor montane wetland is one of the few ecosystems in Iran, which inhabit a number of rare plant species such as Sparganium emersum and Utricularia minor. Strict conservation of such unique vulnerable ecosystems may guarantee the long-term preservation of the genetic diversity of the country.