The purpose is to observe the water-absorbing ability of lichens which may be used to explain the north-seeking habit of the plant.
Things Required:
Glass of water
Eye-dropper
Lichen samples (a pale green scaly or leaf-like crust found on the bark of trees)
Microscope or hand lens
Compass
Directions:
Use the compass to determine the direction that the side of the tree with the growth of the lichen is pointing. Observe your lichen samples under a microscope. Use the eye-dropper to add the drops of water on the lichen samples until they are wet.
This Is What Happens:
Close observation of the lichen reveals that it is not one plant, but a combination of two. One plant consists of very tiny colourless strands and the other is round and green. The lichen absorbs water like a sponge.
Science Behind It:
The strands of colourless cells are the parts of a fungus. Since the fungus has no chlorophyll, it cannot make its own food, but it does act like a sponge and absorbs water and holds it. The threads also attach to the bark of the tree and anchors the plant. The green algae manufacture sugar and starch which it shares with the fungus. The fact that the lichen is generally found on the north side of a tree has nothing to do with the magnetic field, but since moisture is a vital necessity for the plant, it survives best where it can retain moisture the longest. The north and northeast sides of trees have the most shade and thus a lower evaporation rate.
