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Based on stable carbon isotope ratio (delta C-13) measurements, photosynthetic pathway types were determined for 61 species in 54 genera and 24 families of flowering plants from the saline meadows of Northeastern China. Of these total vascular plants, IS species in 17 genera from 6 families were found to have C-4 photosynthesis; 43 species in 38 genera from 20 families had C-3 photosynthesis. Six dicotyledonous species exhibited C4 pathway, 12 monocotyledonous species were found with C-4 photosynthesis. The dicotyledonous C-4 species had relative greater mean delta C-13 value and less total carbon content than both monocotyledonous C-4 and C-3 Species. Most dicotyledonous C-4 species were annual forbs and halophytes. Some C-4 species had been previously documented, but their delta C-13 values varied remarkably from those of the present study. Even though there are some fluctuations for the delta C-13 values of some C4 species, delta C-13 value was still more reliable for C-3 and C-4 identification than the use of the enzyme ratio method and Of low CO2 compensation concentration.