Flower Lab
Biology
Name
Date
Block
Reproductive Structures of a Flower
Introduction: Flowers are the reproductive organs of
angiosperms, or flowering plants. In the mid-1800s,
Gregor Mendel used the flowering pea plant to explore
the principles of inheritance. In order to ensure crosspollination, Mendel removed male or female structures
from different plants. He used brushes to pollinate the
plants whose traits he wanted to cross. Learning the
reproductive structures of the flower is important to fully
appreciate Mendel’s work with flowering plants. During
this activity, you will investigate the reproductive
structures of flowers.
Pre-Lab:
1. Differentiate between pollination and fertilization.
2. List the function of the following flower structures: anther, ovary, ovule, pollen, stigma
3. Of the above list of flower structures, note which comprise the pistil and which make up the
stamen.
Procedure:
Part A: Observing the External Anatomy of a Flower
1. Record the common name of the flower you are observing:
2. Refer to figure 1 as you examine your flower. Identify the receptacle, or structure to which
all other flower parts are attached. Note the sepals, which are small, leaf-like structures
above the receptacle. All of the sepals together are called the calyx. The calyx encloses the
flower bud before the flower opens. Observe the brightly colored petals inside the calyx. All
of the petals together are called the corolla. These structures make up the non-reproductive
structures of the flower. Note the number and color of both the sepals and petals in the data
table. Also, describe the venation (vein arrangement) in the leaf. Make a sketch of the leaf
on drawing paper, showing the venation.
Part B: Reproductive Structures of a Flower
1. Using figure 2, identify the male reproductive
structures, or stamens. Each stamen consists of an
anther and a filament. Identify the female
reproductive structure, or pistil. Each pistil consists
of an ovary, a stigma, and a style. Describe and
count each reproductive structure in the data table.
2. Remove the petals from the flower and sketch and
label the male and female reproductive structures on
drawing paper.
3. Note the presence of pollen on the anther. Shake out
a few grains of pollen on a sheet of paper.
4. Carefully remove the pistil. Use a scalpel to cut the
ovary in half at its widest point as shown in figure 3.
5. Observe the number and arrangement of the ovary
chambers. The white, oval objects inside the
chambers are the eggs. These are surrounded by the
ovule. Place the cross-section of the ovary under a
dissection microscope and sketch and label a diagram
of the ovary on drawing paper.
6. If there is time, place one of the stamens under the
dissecting scope. Sketch and label your observations.
Part C: Comparison of Flowers.
Look at another type of flower on display. WITHOUT damaging the flower, note the venation
pattern of the leaves, the number of petals, the number of stamens, and the number of pistils.
Record observations in the data table. Be sure to record the name of the second flower.
DATA TABLE
Flower Part A & B:
Flower Part C:
Plant Parts
Description
# of Parts
Description
# of Parts
Sepals
Petals
Stamens
Stigma
Pistil
Leaf
Analysis & Conclusions: Answer each question in complete sentences on a separate sheet of paper.
1. Look up the differences between monocots and dicots in your textbook. What are the two
major differences between these two types of angiosperms in regards to flowers and leaves?
2. Which of the observed flowers is a monocot? A dicot? Back up your answers with evidence
from the lab.
3. Why do you suppose Mendel chose to work with a plant instead of an animal specie? What
are the advantages of working with plants instead of animals?
4. Explain why a heavy rainfall on a fruit orchard in the spring might result in a poor fruit yield
in the fall.
5. For what biological reasons do farmers object to people picking apple blossoms during the
apple blossom season?
6. Why do flowers that are pollinated by insects have large, brightly colored, fragrant flowers?
7. Some flowers have both stamens and pistils; they are called perfect flowers. Imperfect
flowers have either stamens or pistils. (A) Are the flowers you observed perfect or imperfect?
(B) What is an advantage and disadvantage to each type of reproductive strategy (either
perfect or imperfect flowers)?