Answer

Stoma refers to the minute pores that can be found on the epidermis of a leaf. These pores vary in size and allow for the movement of water and gases in and out of the intercellular spaces. The following is the procedure for viewing (as well as estimating stomatal frequency) stoma on the surface of a cell.

Requirements

• Clear nail polish
• A leaf
• A compound microscope
• Tweezers
• Microscope glass slide
• Microscope cover slip

Procedure

• Apply clear nail polish on to the surface of the leaf (flattened leaf)
• Allow the nail polish about four hours to dry
• Using a pair of tweezers, peel off a film (thin skin) from the surface of the leaf
• Gently place the film onto a microscope slide and cover with a cover slip
• Start with low power and increase to 100x (frequency of stoma can be counted at 100x)

• Record your observations

While the compound microscope would be more effective for viewing the frequency of the stoma, a stereo dissecting microscope can also be used for this purpose. For instance, by viewing a Zebrina plant leaf (older leaf) it's possible to view the stomata as green patches with a purple background.

Observations:

When viewing the surface of the leaf under the stereo microscope, students will be able to clearly see hair-like structures (trichome) on the leaf surface that serve a number of functions ranging from trapping insects to trapping water/moisture. Youwill also observe the intricate leaf veins (vascular bundles) running across the surface of the leaf.

With some leaves (such as the maple leaf), it's possible to isolate the vascular bundles (vein structures) for viewing under the microscope.