Ganong's Potometer

Product Code : SCL-PLE-12567

Quick Answer: Ganong's Potometer is a glass apparatus on a wooden base for demonstrating transpiration rates and rates of water absorption by a cut shoot under different external conditions. Movement of an air bubble along a graduated capillary tube shows the rate.

Last updated: October 2026

Key Features

• Capillary tube graduated in millimetres, with a 1mm bore
• Water reservoir of approx. 19mm diameter with a glass stopcock for resetting the air bubble
• Plant shoot sealed into a stopper that fits the end tube
• Mounted on a wooden base by clips
• Base approx. (L)311mm, height to top of reservoir 165mm

Technical Specifications

About This Product

The whole apparatus is filled with water and a cut shoot is sealed into the stopper. An air bubble is introduced by lifting the open end of the capillary out of a beaker of water and back in, and its movement along the scale shows how fast the shoot takes up water. Opening the stopcock lets water in from the reservoir to reset the bubble, and coloured water makes the bubble easier to see.

Frequently Asked Questions

How is the air bubble reset in Ganong's Potometer?

Opening the glass stopcock admits water from the reservoir, which moves the air bubble back to the required position.

Which conditions can be investigated?

Different environmental factors can be investigated, for example by adding petroleum jelly to the upper surface of the leaves or by placing the plant inside a plastic bag.

How is a good seal made around the stem?

Petroleum jelly should be used to make a good seal between the plant stem and the apparatus.

Related: Physics Lab Equipment, Liquid Level Apparatus.

For a quotation on the Ganong's Potometer, contact School Lab China.