Figure 2. Growth of the three duckweed species in the four zinc (Zn) treatments over 17 days. Shown are means and standard errors for each sampling date, across settings and compositions. Orange lines, 0 mg/ L Zn, blue lines, 0.45 mg/L Zn, green lines, 1.82 mg / L Zn, yellow lines, 11.35 mg/L Zn.