The story for kids
A stoma. Under a leaf, there are tiny little mouths that open and close. In the daytime they open: air goes in, and oxygen comes out. At night, and when it's very hot, they close, so the leaf doesn't lose water.
Facts
- On the underside of a leaf there are tiny mouths that open and close.
- In the daytime they open: air comes in, and oxygen goes out.
- At night and in hot weather they close, so the leaf doesn't lose water.
Numbers
- Size
- ~0.02 mm
- Where
- Underside of the leaf
- On one leaf
- thousands
For grown-ups
A stoma is an opening between two guard cells. When the guard cells fill with water, the opening widens. Carbon dioxide enters through the stomata, while oxygen and water vapour exit.