Note
Evapotranspiration of the freshwater macrophytes Eichhornia crassipes (Mart.) Solms and Lemna minor L. was examined in tank cultures in Ft. Pierce, Florida. Evapotranspiration of both species during the year 1979 was significantly correlated with open water evaporation, solar radiation and mean temperature. Evapotranspiration of Eichhornia fluctuated by ca. 40% when its canopy structure was varied by manipulating plant stocking density or nutrient availability. Similar variations in canopy structure which commonly occur in natural stands of Eichhornia limit the value of evapotranspiration estimates made over a wide temporal or areal basis.