Experiments were designed to investigate the relative NaCl tolerance of five varieties of English ivy (Hedera helix): buttercup, sweetheart, golddust, glacier and goldheart. Cuttings from these plants were first grown in agar media with selected levels of added NaCl. Buttercup was the most resistant and sweetheart the most sensitive to all levels of NaCl. These differences in NaCl tolerance were further explored using a callus culture system. Actively growing sweetheart and buttercup callus tissue were placed on basal tissue culture media containing 2,4-D and selected levels of NaCl, Na2SO4 and KCl. Results from these experiments suggest that Cl has specific ion effects and is more toxic than Na+. The growth of sweetheart tissue that had been previously γ-irradiated was compared with control tissue on a basal medium containing 5 g/l NaCl. γ-Irradiation of sweetheart tissue prior to culture increased growth in the presence of 5 g/l NaCl over non-irradiated tissues. © 1989.