Stoma
A stoma is a microscopic, specialized structure located on a plant's surface. The stoma consists of two specialized cells--the guard cells that surround the stoma, and the stoma itself.
Stomata
Stomata, the plural word for "stoma," is the Greek word for "mouth." Since a plant's stomata act as tiny mouths for the plant, this name is appropriate. Stomata can be found on every above-ground part of a plant, including the leaves, stem and petals.
Function
A plant uses its stomata to release and take in gases when necessary, such as carbon dioxide, oxygen and water vapor, reports EOEarth.org. A plant takes in carbon dioxide through its stomata, which it uses to create food through the process of photosynthesis.