A stoma is an opening through which carbon dioxide goes in and oxygen and water vapor escape.
From the scientistatwork.blogs.nytimes.com
Plants lose 95 percent of the water they take in to evaporation through these pores, also called stoma.
From the sciencedaily.com
The rate of transpiration is directly related to the evaporation of water molecules from plant surface, especially from the surface openings, or stoma, on leaves.