Information on the degrees and patterns of ion accumulation in various parts of a plant is important in evaluating salinity tolerance, as well as salinity tolerance mechanisms. ‘Challenger’ Kentucky bluegrass (Poa pratensis L.) (KBG), ‘Arid’ tall fescue (Festuca arundinacea Schreb) (TF), ‘Fults’ alkaligrass (Puccinellia distans (L.) Parl.) (AG), and a saltgrass (Distichlis spicata (Torr.) Beetle) (SG) collection were grown under various salinity levels in greenhouse hydroponic experiments. Salinity treatments were applied using 1NaCl:1CaCl 2 solution at different concentrations. . Ion concentrations in shoots and roots of each grass grown at different salinity levels were examined. As salinity increased, Na + , Cl , and Ca ++ concentrations increased linearly, while Mg ++ and K + concentrations decreased in shoots, sap, and roots of all species. Salinity tolerance of these species was associated with their ability to exclude Na + and Cl from shoots and maintain a relatively high level of K + . Potassium to sodium ratio in all species was higher in shoots than in roots, indicating these plants achieved K + selectivity via multiple processes in multiple locations. Maintenance of a K + /Na + ratio close to or above 1 was important for plant survival. Results indicated that, SG, AG, TF, and KBG could maintain a shoot K + /Na + ratio of 1 when salinity levels were less than 22.3, 13.6, 7.4, and 3.7 dS/m, respectively. Leaf ion secretion rate of SG increased as salinity level increased, reaching 5.05, 6.86, and 1.22 mg/g dw/day for Na + , Cl , and Ca ++ , respectively, at 23.5 dS/m. No Mg ++ or K + were secreted. Regulation of ion concentrations (via ion restriction, exclusion or secretion) and maintenance of higher K + /Na + ratio in shoots appeared to be important mechanisms contributing to the differences in salinity tolerance observed in these species. + /Na + ratio, ion secretion rate, salt glands, salinity tolerance.