Evapotranspiration is the sum of evaporation from the land surface plus transpiration from plants. Precipitation is the source of all water. Some definitions include evaporation from surface-water bodies, even the oceans. But, definition of evapotranspiration will not include evaporation from surface water. Evapotranspiration is defined as the water lost to the atmosphere from the ground surface, evaporation from the capillary fringe of the groundwater table, and the transpiration of groundwater by plants whose roots tap the capillary fringe of the groundwater table.
The transpiration aspect of evapotranspiration is essentially evaporation of water from plant leaves. Studies have revealed that transpiration accounts for about 10 percent of the moisture in the atmosphere, with oceans, seas, and other bodies of water such as lakes, rivers, and streams providing nearly 90 percent, and a tiny amount coming from sublimation.