) are tiny pores, mostly on the undersurface of leavess
, used for gas
exchange. Air containing carbon dioxide
enters the plant
through these openings for photosynthesis
. Waste oxygen
produced by photosynthesis in the chlorenchyma
cells of the leaf interior exits through these same openings. Also, excess water is released into the atmosphere through these pores in a process called transpiration
. The opening and closing of a stoma is controlled by guard cells
that surround the opening and involves sodium
Stomata can be seen under a microscope by taking nail varnish impressions of the leaf.
In medicine, a stoma is a surgically created opening into the body. The best known form of a stoma is the opening created by a colostomy to let feces out of the body.