Cultured tissues of taro, Colocasia esculenta var antiquorum, were grown on modified Linsmaier-Skoog medium with and without the addition of 50-350 mOs (5-35%) artificial seawater (ASW). Cell wall thickness and cross-sectional area were variable, but not significantly different over the range of ASW concentrations from 0 to 300 mOs. However, cells at 350 mOs ASW did have significantly thinner walls and smaller cross-sectional areas. Of the organelles observed, plastids appeared to be the most sensitive to increasing ASW concentrations. There were more plastids per unit area at 350 mOs ASW than at any other concentration, but their size was reduced. The ratio of amyloplasts to chloroplasts increased with increasing ASW levels. Mitochondrial and nuclear membranes did not seem to be affected by the ASW concentrations used. At high ASW levels, nucleoli showed a loss of electron density in their central regions. © 1987.