Stomata

Photosynthesis takes in carbon dioxide and gives out oxygen. But a leaf looks solid — so where do these gases get in and out?

Activity 10.6 is a teacher demonstration. Take a leaf from a plant such as rhoeo, money plant, onion, hibiscus, coleus, or any grass, and put it in a beaker of water.

Carefully peel a very thin layer from the lower surface of the leaf and put it in a watch glass of water.

Put a drop of water on a microscope slide and, using forceps, move the peel onto it. Add a drop of ink with a dropper (so the parts show up), cover with a coverslip, and look through a microscope — the openings are far too small to see with your eyes.

You see tiny pores all over the peel. They are called stomata.

Stomata on the leaf surface let gases in and out. The carbon dioxide taken in for photosynthesis, and the oxygen given out by it, both pass through the stomata.