Perspiration It is the evaporation of water from the leaves, stems or flowers of a plant.
You may have seen my transpiration experiments Using celery and colored water, and white flowers before. Today I have a slightly different way to demonstrate this important sscientific conceptIt's a great way to show transpiration in action, and all you need is an indoor or outdoor plant and a resealable plastic bag.
Demonstration of plastic bag transpiration
You will need to
Small resealable plastic bag
Indoor or outdoor plant
Instructions
Sweating occurs more quickly on a hot day, so this activity is a great summer science activity.
Carefully cover a group of small leaves or a large leaf with the plastic bag.
Check the bag every two hours.
You will first see condensation build up and then water collect at the bottom of the bag.
The water that has been collected in the bag is water from transpiration that has risen up the stem from the roots and also water produced during breathing.
What is perspiration?
This Demonstration of plastic bag transpiration shows that water was released from the leaf while it was covered.
Transpiration is the movement of water through a plant stem from the root to the leaf when water is lost from the plant due to evaporation and diffusion of water from the plant surface.
Water is absorbed by the plant root and moves through the cells of the root hairs by the process of osmosisIt then passes into the xylem vessel, which is the conduit that carries water to the stem. Water rises through the xylem vessel by adhesion (attraction to the sides of the vessel) and cohesion (water molecules attract each other).
When water evaporates from the surface of the leaves, the change in pressure pushes the water column upward to replace the lost water. This creates a constant transpiration stream of water through the plant.
More experiments with plants
Discover How temperature affects transpiration rate.
Discover How seeds are dispersed Making a sticky seed pod.
Learn about the different parts of a plant through dissecting a flower.
Discover How plants breathe.
Scientific concepts
Perspiration
Evaporation
Transport in plants
