DEPARTMENT OF NATURAL AND APPLIED SCIENCE
COURSE: PLANT STRUCTURE AND FUNCTION
PRACTICAL 5
LECTURER: ZIVUKU .M (2015)
Introduction
You are provided with fresh leaves of a dicotyledonous plant. In this lab you will
explore the structure of stomata and examine how they are distributed throughout
the leaf.
Materials/ apparatus
-
Microscope
Dicots leaves
Scalpel blades
Transparent microscope slides
Cover slip
Glycerine/Safranin dye
Distilled water
Method
1. Take one leaf from the provided dicot leaves.
2. Use your fingernails to peel off the epidermis, or use a sharp razor blade to
peel off the epidermis.
3. Mount the peel in a drop of water on a microscope slide with a coverslip.
Alternatively, make an epidermal impression with nail varnish or another clear
substance, and place that on a microscope slide to view it
4. Peel off three epidermal samples/ impression of the same plant to get a
representative sample. Try to be consistent about which part of the leaf to
use.
Activity A -Drawing stomata
5. View the epidermal sample or impressions using microscope and locate the
stoma.
6. Draw a picture of the stomata and a few surrounding cells. Label the stoma
the pit, guard cells and chloroplast.
Activity B –determination of stomata density
7. Estimate the field of view.
8. Calculate the true area of the field of view. You can calculate this using the
formula area = r2, when you have measured the true radius of the field of
view (r).
9. Count the stomata visible in each of three areas of the epidermal layers or
impression.
10. Calculate the stomatal density for each area of the epidermal layers or
impression sampled.
11. Analyse average density for each impression and for each plant.
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12. Repeat 1,2, 3, 4, 7, 8, 9, 10 and 11 for different types of leaves and record
your results in the form a table.
Your table for stomata density in leaf from plant A;
Plant Number and leaf True
type
radius
Plant A
Leaf 1
Leaf 2
Leaf 3
Average
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Area
view
of Number of Density
Stomata
of
stomata