The stoma or stomata plural are pores found in leaf stems. The opening in between two guard cells is the stoma. Carbon dioxide and oxygen enter through the opening which the plant uses for photosynthesis while water vapour exists. Basically it allows for the intake and outake of gases and allows for air to move inside their tissues. Plants in a desert area, would have less stomata due to the fact that they want to store water not loose it while a marsh area would be the opposite.
