Three groups of waterhyacinths (small, ca 15 cm tall; medium, 45–60 cm, and “super”, 90–120 cm) were compared by using horizontal starch gel electrophoresis and examining the root tips of healthy plants. Banding patterns for seven isozyme systems were examined and a total of 14 consistent and reproducible zones of electrophoretic activity were observed on the gels. Based upon these data, no discernable differences existed amongst the three forms, despite the disparity of size and their occurrence in different environments.