Explore the Plant Water Transport: Xylem Simulator
Follow water from root to leaf through the xylem, and see how transpiration, root pressure and vessel width set the water's speed and pressure.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
Illustration. Open the tool for the real thing.
See it in action
The Plant Water Transport: Xylem Simulator with sample data entered and the result showing.
What is the Plant Water Transport: Xylem Simulator?
Follow water from root to leaf through the xylem, and see how transpiration, root pressure and vessel width set the water's speed and pressure. It runs in your browser, so a change to a setting or a drag on an object shows up at once.
Foresters and plant physiologists use cohesion-tension theory to explain how trees move water without pumps, and it also explains why droughts can cause fatal embolism in tree xylem.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
Cohesion-tension theory: water evaporating from the leaf pulls the whole connected water column up the xylem under tension, held together by cohesion between water molecules.
At night, with stomata shut, root pressure alone can push water upward, sometimes causing droplets called guttation.
The Hagen-Poiseuille law says flow speed rises with the square of the vessel radius and volume flow with the fourth power, so slightly wider vessels move dramatically more water.
Try the night preset and see root pressure take over as the driving force.
Try the hot midday preset and watch the tension climb.
Narrow the vessel radius and see how sharply the ascent velocity drops.
Used for
Pick one to see how it fits.
Teachers
For teachers: project the Plant Water Transport: Xylem Simulator on the board, let students predict the result, then run it together and test this: Try the hot midday preset and watch the tension climb. For students: change one thing at a time and write down what changes.
Try it freeHow it compares
A plain look at this tool next to the usual alternative.
| This simulation | Textbook diagram | |
|---|---|---|
| Interactive | Drag, tap and change settings | Fixed picture |
| Install | Nothing to install | Not needed |
| Cost | Free to use | Depends on the book |
Questions people ask
What pulls water up a 100-metre-tall tree with no pump?
Transpiration at the leaves creates tension that is transmitted down an unbroken column of water held together by cohesion - the cohesion-tension theory.
Why don't trees just evolve very wide xylem vessels for maximum flow?
Wider vessels are more likely to develop or trap air bubbles (embolism) that can block the whole column, so many trees favour narrower, safer vessels and rely more on strong transpirational tension.
Is the Plant Water Transport: Xylem Simulator free to use?
Yes. The Plant Water Transport: Xylem Simulator is free, needs no signup or download and runs in your web browser. It is part of the Botany group of AZRS simulations.
Does the Plant Water Transport: Xylem Simulator work on a phone or tablet?
Yes. The Plant Water Transport: Xylem Simulator takes touch input as well as mouse input, so you can use its 4 adjustable settings with a finger. A larger screen makes the controls and graphs easier to read.
How do I use the Plant Water Transport: Xylem Simulator?
1. In the Plant Water Transport: Xylem Simulator, use the controls to change Transpiration rate, Root pressure, Air humidity, Xylem vessel radius. The simulation reacts instantly. 2. In the Plant Water Transport: Xylem Simulator, press "Night (stomata shut)", "Hot midday" to start, reset or change what is happening. 3. Start with this experiment: Try the night preset and see root pressure take over as the driving force. Drag any glowing handle, object or slider with your mouse or finger and the Plant Water Transport: Xylem Simulator responds in real time. 4. Change one setting at a time and watch which readout moves, then compare it with this idea: Cohesion-tension theory: water evaporating from the leaf pulls the whole connected water column up the xylem under tension, held together by cohesion between water molecules.
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Try the Plant Water Transport: Xylem Simulator now
Follow water from root to leaf through the xylem, and see how transpiration, root. Free to use.
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