If plants “sweat”, then how does the water exit the plants? Plants have very small mouths called stomata. These mouths are located on the leaves. When plants breathe during the day, they inhale carbon dioxide and exhale oxygen and water vapor. Humans (and other animals) inhale oxygen and exhale carbon dioxide and water vapor. You can see this by breathing on the surface of a mirror. Like plants, we exhale water, and the water becomes visible on the mirror, just like clouds in the sky are visible forms of water.

The mouths of plants are about 1000x smaller than our mouths, so we cannot see them with the naked eye. However, we can zoom in on them with a microscope!