Autopolyploid prairie cordgrass (Spartina pectinata) possesses a genetic variation for the ability to survive and reproduce under salt stress conditions. However, little is known about the effects of salt stress on germination, plant growth, and stomatal response of polyploid plants. Greenhouse experiment was conducted to 4 prairie cordgrass populations having three cytotypes: two tetraploids (2n=40) collected from New York and Illinois, one hexaploid (2n=60) collected from Illinois and one octaploid (2n=80) obtained from seed source, and were demonstrated plant growth and stomatal responses under various salt concentrations: 0, 100, and 200 mM NaCl.  Octaploid populations retained its growth potential and produced new reproductive tillers under high salt stress, whereas the number of reproductive tillers for New York tetraploid and hexaploid significantly reduced by 50 % at 200 mM NaCl.  The seed germination test was only conducted to two tetraploid and one octaploid populations due to limited number of seeds for hexaploid population. Significant difference was found in seed germination percentage among the populations along all salinity levels. Octaploid seeds were retained 59 % its germination potential under high salt stress up to 500 mM NaCl, whereas seed germination of both tetraploids were reduced by 61 % at 500 mM NaCl. The results demonstrated that octaploid prairie cordgrass is the most tolerant among remaining populations, thus presenting promising donors for salt tolerant traits in future breeding efforts for salinity tolerance in prairie cordgrass.