Investigation - Leaf Transpiration and Light

plant on table

Objective: Determine the amount of water loss due the transpiration.


Leaves from a tree (students can collect from different species)
Vegetable oil
Water (dechlorinated)

Problem: What properties affect the amount of transpiration that occur in leaves?

Properties you can analyze include: surface area of leaf, exposure to light, and species of tree.

How to Determine Water Loss Due to Transpiration:

1. Place dechlorinated water into a beaker, make sure you record the amount of water placed in the beaker (in milliliters)
2. Place leaves in a beaker with water so that their petioles are submerged. In order to get enough water loss to observe and record, you will need to place multiple leaves in the beaker.
3. Pour a small amount of oil over the surface of the water - this will prevent water loss due to evaporation
4. After 48 hours, remove leaves carefully and measure the amount of water left in the beaker, be careful not to include the oil in the measurement.


1. As a group, determine how you will analyze each of the properties. The investigation should be comprehensive and address as many properties as possible. Your goal is to determine which factors affect transpiration.

2. Record your hypothesis and methods you will use to solve the problem. In your lab report, you will include this under the "materials and methods" section.

3. Set-up your experiment.

4. Record and analyze data.

See Lab Report Template for guidelines on writing a lab report.

Other Labs with Plants

Rate of Photosynthesis – using baking soda, elodea and light, measure the bubbles to observe how fast a plant photosynthesizes and releases oxygen

What Factors Affect Seed Germination – grow seedlings with different conditions (light, water, temperature)

Algae Beads and Photosynthesis – use algae cultures and sodium alginate, measure photosynthesis by changes in color of indicator

Photosynthesis with Leaf Disks – this lab uses leaf disks that float to indicate photosynthesis.  Students investigate factors that affect photosynthesis.  (AP Lab)

Photosynthesis and Plant Growth (virtual) – use a virtual app to show how plant growth changes in response to light color and light intensity