The stomata are the pores through which gas exchange takes place.The two guard cells surrounding each stoma contain cholorophyll (unlike the other cells in the epidermis); it is the guard cells that control the size of the stomata.
A "cast" can be taken from the surface of leaves using nail varnish. When the nail varnish is peeled off it can be put under the microscope.
 |
| Nail varnish cast of leaf epidermis from a dicotyledon (top) and monocotyledon (bottom) |
The following images are of prepared epidermal tissue on a microscope slide, the blue colour is due to the dye used to make structures stand out more clearly.
 |
| Prepared slide: leaf epidermis, dicotyledon (top), monocotyledon (bottom) |
Commelina leaves are ideal for observing stomata as their epidermis peels very easily. The following image is one I took from a leaf of a plant I grew from seed. The chloroplasts are clearly visible in the guard cells.
