In botany, a stoma (also stomate; plural stomata) is a tiny opening or pore that is used for gas exchange.

Air containing carbon dioxide and oxygen enters the plant through these openings where it is used in photosynthesis and respiration. Waste oxygen produced by photosynthesis exits through these same openings. Also, water vapor gets into the atmosphere through these pores in a process called transpiration.

The pore is formed by a pair of specialized cells known as guard cells which are responsible for regulating the size of the opening and found mostly on the under-surface(epidermis) of a plant leaf.

See also: Stomata Experiments & Background Information

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