The studies on the effect of heavy metals on plants have shown that they cause intensification of two types of unfavorable processes: ? inactivation of macromolecules and cellular structures, ? induction oxidative stress. All molecular, structural and metabolic changes on the level of molecules, tissues and organs lead to changes of plant morphology. One of the change is inhibition of plant growth, reflected as a reduction of its size, mass of either the whole plant or its part, organs or tissues. In response the plant activates processes restoring its homeostasis. In removing reversible changes a particular role is played by the processes of heavy metal detoxification as well as removal of active forms of oxygen.