Uptake and localisation of rubidium in the halophyte Suaeda maritima

Plants of Suaeda maritima grown in culture solution containing rubidium chloride accumulate rubidium, which can be estimated by flame emission spectrophotometry. This accumulation of rubidium is correlated with the appearance, under the electron microscope, of electron dense deposits in the cells. These deposits are restricted to the vacuoles and only seen after growing plants in the presence of rubidium. The procedures necessary to visualise the rubidium are described and the significance of the localisation discussed in relation to the distribution of ions in the cells of halophytes.