What the stem does

· It supports leaves and flowers.
· It circulates sap.

THE CIRCULATION OF SAP

Cut through the stem of a coffee tree or of a lemon tree. What do we see?

· First of all, on the outside of the stem, there is the bark.

This is the skin of the tree.
Skin protects a man or an animal.
The bark protects a tree stem.
If a goat eats the bark, or you cut it with a hoe, the plant is no longer protected. It is injured.
Many diseases can get in through this injury.
You must not injure the bark.

· Under the bark is the wood.

When the tree is old, the wood is thick, the stem is hard.
Wood makes the stem hard.

Cut stern of a lemon tree

In the wood you can see many little holes.
These are little tubes or vessels.
In a man's body the blood is carried by blood vessels.
In a plant, vessels carry the sap.

· In the centre of the stem is the pith.

If you cut a cotton stem you can see the pith very easily.
It is less hard than the wood.
Often it is not the same colour.