Observing Plant Transpiration

This demonstration shows how plants release water vapor through their leaves in a process called transpiration. By sealing leaves inside a plastic bag and comparing it with a control bag, students can observe condensation forming as water vapor escapes from stomata and condenses on the bag’s surface.

1. Select a healthy, sunny outdoor plant with live leaves.
2. Place a transparent plastic bag over a group of leaves and secure it tightly around the stem with a twist tie.
3. Set up a control by securing another identical plastic bag around a pencil or stick.
4. Place both setups in the same location with a “Do Not Disturb” sign.
5. Leave the experiment undisturbed for about 30 minutes.
6. Return and observe any condensation inside the bags. Record differences between the plant bag and the control bag.
7. Discuss results and link observations to the process of transpiration.

Water Collection: Transpiration Bag - Snow Walker Outdoors & Guide Service :

Get Drinking Water from a Tree - Transpiration Bag Survival Trick - Great Lakes Country:

📄 Transpiration Demo - NASA Jet Propulsion Laboratory: https://www.jpl.nasa.gov/edu/resources/lesson-plan/transpiration-demo/

• Repeat the experiment on sunny and cloudy days to compare condensation levels.
• Try the experiment with different plant species to see which release more water vapor.
• Extend the time period (e.g., 1–2 days) to see greater accumulation of condensation.

• Be cautious when selecting plants; avoid poisonous or allergenic species.
• Do not damage the plant while attaching the bag.
• Conduct the experiment in a safe outdoor area where the setup won’t be disturbed.

• Where did the condensation inside the bag come from? (It came from water vapor released by the leaves.)
• Why was there little or no condensation in the control bag? (There was no living plant releasing water vapor.)
• What structures in the leaves release water vapor? (Stomata, tiny pores on the underside of leaves.)
• How is transpiration different from evaporation? (Transpiration is water loss through plants; evaporation is direct water loss from soil or surfaces.)
• Why is transpiration important for the water cycle? (It returns significant amounts of water to the atmosphere, contributing to cloud formation and rainfall.)
• What might happen to transpiration during drought? (Plants close stomata to conserve water, reducing transpiration and photosynthesis.)