Leaf Structure Lab
INTRODUCTION
Purpose:
Background:
Materials:
Describe the purpose of this lab in your own words.
Using the diagram and the “Leaf Functions” section on pg. 596 of your textbook, describe the THREE functions
of leaves and where each process occurs.
Prepared slides of Zea mays leaves (monocot), and Lingustrum (dicot), digital microscopes, and Geranium leaf
samples.
Procedures:
1. Bring your textbook to your lab station.
2. Obtain a prepared slide of either Zea or Lingustrum (only take one at a time). If you are using the Zea slide then do
part I first. If you are using the Lingustrum slide do part II and III first.
Part I “Internal Structures of a Monocot Leaf”
1. Using the digital microscope, examine the prepared Zea leaf slide on scanning power (40 X). Find the largest vein on the
leaf and center the vein.
2. Set magnification to low power (100 X). Draw and label the leaf on 100 X.
3. Include in your drawing: xylem, phloem, mesophyll and chloroplasts, epidermis and cuticle, guard cell and stoma.
4. Answer questions 1-7 while viewing the slide.
Part II “Internal Structures of a Dicot Leaf”
1. Examine the prepared Lingustrum leaf slide under scanning (40 X).
2. Use the below table to help you identify the various structures of a dicot leaf. It might be necessary to switch to 100 X.
3. Answer questions 10-16.
Table of Leaf Structures
Structure
Description
Upper
Thin, clear waxy coating that helps prevent water
Cuticle
loss
Structure
Veins
Upper
Epidermis
Single layer of brick-shaped cells with few
openings to surface
Lower
Epidermis
Mesophyll
Leaf layers between the upper and lower
epidermis where most photosynthesis occurs.
Long, narrow cells located just below the upper
epidermis; chloroplasts near the edges of the
cells.
Irregularly-shaped, loosely packed cells below
the palisade layer; air spaces between these cells
allow for transfer of gases.
Stomata
Palisade
layer
Spongy
Layer
Guard
cells
Description
Fibrovascular bundles scattered throughout the
mesophyll; contain xylem and phloem tubes,
which transport substances and support the leaf.
Located below the spongy layer, a single layer of
cells similar to cells that make up the upper
epidermis.
Openings in the epidermis that allow for gas
exchange with the environment.
Pair of sausage shaped cells that surround the
stomata; contain chloroplasts.
Lower
cuticle
Identical in structure and function to the upper
cuticle.
Part III “The Stomata”
1. Obtain a geranium leaf and using forceps, peal a small amount of epidermis from the lower surface of the leaf.
2. It should be clear and thin. If it is green it is too thick.
3. Place this piece of epidermis on a slide and make a wet mount.
4. Examine under the microscope and draw it on 400x or higher. Label stoma and guard cells.
DATA COLLECTION
Be sure to include all PROPERLY labelled microscope images and drawings in the section.
DATA ANALYSIS
1. How many cell layers make up the upper epidermis?
2. What is the function of the cuticle?
3. What type of tissue comprises the vein?
4. How can you differentiate between these tissues of the vein? (Hint: Think about color and shape)
5. What are the functions of the tissue that comprise a vein?
6. Where are most of the guard cells and stoma?
7. What is the function of the stomata?
8. How thick (how many cell layers) is the palisade layer?
9. What structures are present in the palisades cells?
10.
Why are these found in this layer?
11.
If you were to travel down the xylem of the leaf where do you think you would end up?
12.
What color is the leaf phloem? This might help you answer question # 5.
13.
What is the function of the phloem in the leaf?
14.
What color is the xylem of the leaf?
15.
What is the function of the xylem of the leaf?
16.
How does the Lingustrum (Dicot) differ from the Zea (monocot) leaf?
CONCLUSION
Address the purpose: Discuss what you learned in this lab in relation to the purpose
Error Analysis:
Suggestions/Modifications: