Abstract:Lanthanum entered plants through the root and accumulated mostly in the cell wall of the root tip. Only a few accumulated in the cortex cell of the root elongation zone and in the cell wall of the mesophyllous cells. There was no detectable lanthanum in the cytoplasm. Observation with TEM (transmission electronic microscopy) indicated that lanthanum, which appeared as electron opaque deposits, was present in the cell wall of tissues in every part of the plant. The higher lanthanum contents occurred in the cell wall of root tips caused a dark appearance of the cell wall. The content of lanthanum in the cell wall of the cortex of elongation zone appeared as granules of different size. Those in the mesophyllous cell wall appeared as much less small granules. X-ray energy spectnnn analysis of the deposits confirmed the induction of lanthanum into the plant tissue cells and that its intensity correlated with the density of the deposits.