Fig. 3. Mean cadmium concentrations in the roots and shoots of plants from the hydroponic cadmium uptake study. Error bars indicate standard error. (The n values for the roots and the shoots are 26, 25, 28, and 27, respectively, by treatment. Treatments are as follows: Control, no Cd²⁺; Low, 5 µM Cd²⁺; Medium, 25 µM Cd²⁺; High, 50 µM Cd²⁺.)