An exiting experiment that shows what causes plants to burst when over-watered.
Things Required:
Rhubarb stalks (found in vegetable department of grocery store)
Bowl of water
Directions:
Place the rhubarb stalks in the bowl of water. Leave the stalks undisturbed for one day.
Observe the shape of the stalks after being in the water.
This Is What Happens:
The ends of the stalks split and curl.
Science Behind It:
Rhubarb stalks contain long vertical cells that are all grouped together in what is called fibrovascular bundles. These bundles of long cells absorb water at different rates. Some of the bundles absorb more water than do other bundles causing the stalk to swell and split apart at the weak points. The pressure of the water inside the cells of the stalk is called turgor pressure, and this pressure can be as high as 60 to 150 pounds per square inch (4 to 10 atmospheres). With this much inside pressure, the stalk of rhubarb bursts open and curls because some of the cells have less water. The cells with less water do not expand as much and form the bottom part of the curl.
