The responses of the salt-accumulating halophyte Seidlitzia rosmarinus to salt stress (500 mM NaCI) were studied. Observations were carried out over the span of 72 h. Three phases of responses were identified. Parallel observations of physiological parameters and cell ultrastructure allowed us to conclude that S. rosmarinus is capable of resisting salt stress owing to changes in its osmoregulatory systems (ions or organic osmolytes). In addition, these observations showed that salt ions are localized in the central vacuole of leaf cells (via pinocytosis) and also in small cytoplasmic vacuoles of leaf and root cells.