The inevitable fate of much of the ethylene glycol used for deicing bridges, aircraft and airport runways, and from leaking and overheating automobile radiators is as runoff to adjacent surface waters which commonly contain higher plants, including members of the duckweed family, the Lemnaceae. However, ethylene glycol is usually thought of as being a relatively benign pollutant and therefore its effects on higher plants have received little attention. The EC50 for ethylene glycol with respect to the inhibition of frond reproduction in axenically-grown Lemna gibba is 176 mM. HPLC and GC/MS studies indicate that ethylene glycol is not metabolized by duckweed. However, after having grown in the presence of ethylene glycol, the fronds of L. gibba are a darker green, translucent color, tend to sink, and generated gas bubbles in their growth media. It is hypothesized that these effects are due to a disruption by ethylene glycol of the pectin layer between cells as evidenced by the appearance of intercellular gaps in the aerenchymatous tissues. Other polyols, including propylene glycol and glycerol, produced the same effects as ethylene glycol. The result of the creation of the intercellular gaps is to increase the uptake of solutes and water from the growth media into the intercellular air spaces. The enhanced uptake of water caused the fronds to sink as well as change the optical properties which resulted in the darker green appearance. The enhanced uptake of nutrients led to the stimulation of growth at concentrations of ethylene glycol below 80 mM. The enhanced uptake of sucrose led to enhanced metabolism and an increased evolution of carbon dioxide as reflected by the bubbles in the growth media. However, the enhanced uptake of organic and inorganic pollutants led to their enhanced toxicities. Therefore, though ethylene glycol may be of relatively low direct toxicity, it can through various interactions, potentiate the toxicities of other pollutants