Botanical Leaf Stomata Transpiration Potometer

60 mins Ages 10-14 Indoor

A challenging, hands-on discovery and STEM project designed for curious young minds aged 10 to 14.

Materials Needed

  • • Fresh woody leafy plant cutting (e.g., lilac, ficus, or rose) (1 branch)
  • • Clear vinyl flexible tubing (approx. 1 meter, narrow bore) (1 piece)
  • • Metric millimeter ruler (1 unit)
  • • Petroleum jelly (Vaseline) (1 dab)
  • • Water and tape (1 set)

Pro Tips

  • → Cut the woody plant stem at an angle while submerged in a bowl of water to keep the xylem columns intact.
  • → Insert the stem tightly into water-filled vinyl tubing and seal the junction with petroleum jelly to make it airtight.
  • → Introduce a single tiny air bubble into the opposite horizontal end of the tube: measure the bubble's progress along a ruler to quantify transpiration.

Safety First

Cut the plant stem under water to prevent air bubbles from blocking xylem vessels.

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Step-by-Step Instructions

1

Step 1

Submerge a leafy woody plant cutting in a bowl of water and cut the stem base at a 45-degree angle underwater.

2

Step 2

Push the stem into a water-filled clear vinyl tube, sealing the junction with petroleum jelly to prevent air leaks.

3

Step 3

Tape the horizontal tube alongside a metric ruler and draw in a tiny 2 mm air bubble at the open intake end.

4

Step 4

Log the bubble's position along the ruler every 5 minutes to calculate transpiration water uptake in millimeters per minute.

What they are learning

Ganong potometer transpiration measurement Capillary volumetric water uptake rate Environmental factors on plant transpiration (wind, heat, light)