Materials needed
Per group:
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1 flower
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Hand lens
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Tweezers
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Clear tape
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Attached data sheet
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Crayons or colored pencils
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White drawing paper
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Variety of fruit with seeds (e.g., cucumbers, tomatoes, squash, green peppers, Valencia oranges)
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Paper plates
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Knife (for teacher to cut fruit)
Instructional activity Content/Teacher Notes
Ultimately, all life on Earth depends on plants to provide food, shelter, and oxygen. Because of this, plant reproduction is very important to all living things. The first step of plant reproduction is pollination. The process of pollination begins when pollen grains (male reproductive cells) reach the stigma (the female reproductive part) of the same species of plant. Some plant species have one flower with just male parts and another with just female parts, while others have both male and female parts within the same flower. Animals assist in the pollination of more than 90 percent of the flowers on Earth. Wind and rain assist the rest. In order to attract pollinators, plants have adapted in many ways: they produce sweet nectar, colorful petals, and attractive aromas.
Some good flowers for dissection include tulips, iris, daffodils, gladioli, daisies, and petunias.
Introduction
1. Divide the class into groups of two or three students. Give each group a paper plate holding a number of slices of various fruits, making sure that seeds are present in the slices.
2. Ask students what the foods have in common. Some groups will realize that all of the foods have seeds buried inside the “flesh” of the fruit.
3. Explain that the fruit is formed from a specialized structure in the plant, which the students will be exploring in their investigation. Fruits contain seeds and a fleshy pulp. Some foods that we call vegetables are actually the fruit of a plant — for example, cucumbers, tomatoes, and peppers.
Procedure
1. Give each group a fresh flower, tweezers, hand lens, clear tape, and data sheet.
2. Instruct students to carefully remove the sepal, located at the base of the flower, and carefully tape it to the appropriate box on the data sheet.
3. Then, have students complete the remaining boxes: number, color, and function.
4. Allow time for students to complete the flower dissection by removing and inspecting the other flower parts listed on the data sheet.
Observations and Conclusions
1. As the students work on their dissection, move around the room, posing questions such as:
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Can you locate pollen on the stamen?
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Do you think an insect could easily move the pollen from the stamen to the pistil?
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What characteristics does your flower have that might attract animals?
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Is the pistil of your flower well adapted for capturing and holding onto pollen?
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Is the stamen of your flower positioned higher or lower than the pistil?
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What function did the sepals perform for the flower before it opened? (They protected the bud.) After it opened? (They help hold the flower up.)
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Can you find the ovary of your flower? What will this become? (“Flesh” of the fruit)
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Open the ovary and count the ovules inside. What will these become? (Seeds)
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Is the neck of the pistil hollow or solid? (Hollow, to allow the pollen tube to grow down and release the male cell to fertilize the egg)
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Touch the top of the pistil. Is it a bit sticky? (Yes)
2. As the students complete their data sheet, have them also make and label a line drawing of a flower on white drawing paper to reinforce their understanding of the flower’s structure.
3. Show students a fern plant complete with spore cases on the backs of the fern fronds. The spore cases are small, raised, round, and brown. These are the “seeds” of the fern. The particles that fly out when the spore cases break open are called “spores.”
Sample assessment -
Check the labeled line drawings to assess the students’ understanding of the components of a flower.
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Assess students’ knowledge based on answers to the questions listed above under “Observations and Conclusions.”
Follow-up/extension -
Have students cut out representations of the different parts of the flower from construction paper. Then, have them assemble the flower and name the various parts and their functions.
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Have students create a flip book with illustrations of the stages of pollination. Give four 3 x 5 inch index cards to each student, and have them cut the cards into quarters, producing a total of 16 small cards. Instruct students to draw on the far right edge of each card a flower in the various stages of pollination. Then have students turn their flip book over and draw the fruit forming from the flower. Direct students to stack their cards in order, holding the left side of the cards firmly with their thumb and forefinger. By flipping through the cards on the right side, students will see the flower become pollinated. If they turn their flip book over, they can see the ovary swelling and gradually turning into fruit.
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Challenge students to improve upon nature’s delivery of pollen to the pistil. Have students draw their concept and give a written explanation.
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Have students dissect a seed to find the embryo. Soak dried beans overnight, and have the students open the seed to find the tiny plant embryo inside.
Resources -
Chesapeake Bay Program: America’s Premier Watershed Restoration Partnership. http://www.chesapeakebay.net/. Provides articles and other resources on the Chesapeake Bay’s natural resources.
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Connections: Connecting Books to the Virginia SOLs. Fairfax County Public Schools and The College of William and Mary. http://www.fcps.edu/cpsapps/connections. Presents a database of more than 1,000 works of children’s literature and their connection to the Virginia Standards of Learning.
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The Great Plant Escape. University of Illinois Extension. http://www.urbanext.uiuc.edu/gpe/index.html. Offers information on plant life and soil in a cute mystery format with Detective LaPlant.
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Outstanding Science Trade Books for Students K–12. National Science Teachers Association (NSTA). http://www.nsta.org/ostbc.
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Project Learning Tree. American Forest Foundation. http://www.plt.org/. Provides details on this national environmental education program.
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Project WET (Water Education for Teachers). http://www.projectwet.org/. Offers watershed resources through an online store.
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Search for Literature: Literature for Science and Mathematics. California Department of Education. http://www.cde.ca.gov/ci/sc/ll/ap/searchlist.asp. Offers a searchable database.
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Virginia Naturally: Linking Virginians to the Environment. http://www.vanaturally.com/. Offers environmental resources for teachers.
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Virginia Naturally School Recognition Program. Virginia Department of Game and Inland Fisheries. http://www.dgif.state.va.us/education/van_school_recognition.html. Provides information about the Virginia Naturally program to recognize environmental stewardship in schools.
Flower Dissection Data Sheet
Name: Date:
As you dissect your flower, complete the following data table:
Flower Part | Tape each part here | Number (count) | Color | Function | Sepals |
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| Petals |
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| Stamen |
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| Pistil |
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| Sample Released SOL Test Items
  
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