From Seed to Seed:
Plant Science for K-8 Educators

Activity 24: Potato Races

Grades: 5-8

Associated Lesson Topics:

• Underground stems
• Asexual propagation
• Solanaceae (potato or nightshade) family
• Plant parts as food

National Standards:

• SCIENCE: Standard A, Standard C
• GEOGRAPHY: Standard 1
• HISTORY: Standard 1

Planting the Seed...

Provide each student with a potato that has already begun to sprout. To encourage potatoes to sprout, place them in a warm location. What words would you use to describe your potato? What can you tell me about the surface of the potato? What are those bumps? What is happening to the bumps? What would happen if we planted the potato? Do you think we would come up with a new potato? Let's try...

Teacher Information:

There are two ways that plants can reproduce. In sexual reproduction, the union of gametes results in seed production, whereas, in asexual reproduction, an identical replica of the plant is produced through the propagation of plant parts. Plants with rhizomes (iris), bulbs (garlic), tubers (potatoes) and corms (crocus) reproduce asexually, or vegetatively. The purpose of this activity is for students to explore asexual reproduction in tubers. This experiment can serve as an extension to Activity 23 (An Eye for an... Plant???) or can be used on its own for older students.

Tubers are actually enlarged underground stems whose primary purpose is storage. The "eyes" that we see on potatoes are actually buds that will form new shoots.

Necessary Materials:

• Potatoes that have already begun to sprout.
• Knives.
• Potato seeds.
• Planting materials.

Procedure:

• When the potatoes begin to sprout, have students cut them into pieces. In order to produce new potato plants, each piece must have at least one "eye" in it. Invite students to experiment with the size of the potato piece. For example, how small can a potato piece be and still produce a new plant?
• Plant each potato piece in the garden or in a large pot if you are conducting this experiment in the classroom. The new tuber will grow above the piece that you plant, so plant it a couple of inches deep.
• Keep the soil moist but not drenched. In the classroom, place the pots on a windowsill. Watch for new potatoes!
• At the same time that students are planting their potato pieces, have them plant potato seeds. The seeds should be planted in the same area of the garden or in the same size pot with the same soil. Keep all variables other than the plant source constant (watering, fertilizer, amount of light).

Harvesting the Crop...

Which method produces potato plants the fastest? Have students record when they first see growth from the potato pieces versus seeds. Which method do you think farmers should use? There are actually two reasons farmers usually choose to propagate potatoes asexually. In addition to being a faster method for growing potatoes, asexual propagation results in the production of identical plants. With seeds, the outcome is uncertain.

Alternatively, students can explore the uses that other cultures have for potatoes or how this plant has played a role in societies throughout history. Potatoes were, after all, a staple food in Ireland for a very long time. The loss of this crop because of disease not only devastated the entire country, it triggered changes that led to the Industrial Revolution in Europe and the United States! It is difficult for students to imagine a single plant having such a huge impact on an entire society. Did Native Americans have any special uses for these foods?

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