We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is a Potometer?

By H. Colledge
Updated May 21, 2024
Our promise to you
All The Science is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At All The Science, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

A potometer, or transpirometer, is a device used to measure the rate of transpiration, or the rate of loss of water, from the leaves of a plant. Potometer readings will typically vary according to factors in the environment, such as temperature, light, humidity, breeziness and the available supply of water for the plant. A very simple potometer can be made by inserting a leaf-bearing plant stem snugly into a piece of plastic tubing and connecting the tubing to a pipette, or graduated length of glass tubing, full of water. It is important to prevent any air from entering the apparatus, so potometers are often assembled underwater, with everything submerged apart from the leaves. Changes in the level of water in the pipette are noted over time to assess the rate of water uptake by the plant, which corresponds to loss of water from the leaves.

Plant roots take up water and minerals from the soil and transport them up the stem to the leaves through specialized tissue known as xylem. Xylem consists of numerous tiny channels which run vertically all the way up the plant. When water reaches the leaves, it evaporates through openings called stomata. As water molecules tend to stick together, this evaporation from the top of the plant exerts an upward pull on the vertical columns of water in the xylem. By setting up a potometer experiment, transpiration rates can be measured when various environmental factors are changed.

One type of potometer design commonly used in the biology classroom is the bubble potometer, where the rate of movement of a bubble of air inside a column of water is used to measure the transpiration rate of a plant. The bubble is introduced into the system by allowing a small amount of air into the end of the glass tubing connected to the plant, before submerging the tubing in a container of water. As water is taken up by the plant, the bubble will be seen to move along the tube, and marks made along the side of the tube allow the bubble's rate of progress to be measured.

Using the potometer, transpiration rates can be assessed in different situations. Leaf stomata tend to open in response to light, so more light means increased transpiration. An insufficient water supply causes stomata to close, which decreases transpiration. It is generally found that higher temperatures and drier air around the leaves increase the evaporation of water and cause a faster transpiration rate. Still conditions allow water vapor to collect around the stomata, discouraging evaporation, so windy conditions tend to speed up transpiration rates.

All The Science is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

Discussion Comments

By Glasis — On Mar 16, 2014

Technology is changing so quickly it is probably a good thing to have more simple experiments like this in the classroom.

Exposing young students to how a farm work is important. There is nothing more basic than growing a plant from a seed and watch as it turns into a fully mature plant.

Agriculture is a hard field to go into and it needs young minds working on the issues we face in the global farming community.

All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.

All The Science, in your inbox

Our latest articles, guides, and more, delivered daily.