The ultrastructure of cells of ground meristem in the peripheral zone of shoot apical meristem in Elodea canadensis Rich. was studied after treatment with cadmium in concentrations 0.5, 1, 2, 3, 5, and 6 g(Cd2+) m-3. After 5 d treatment, changes in the structural organisation of the plastid apparatus were found, namely in proplastid, amyloplast, and amoeboid stages of plastid development. and D. Stoyanova, E. Tchakalova.