A storm tears open an old neem tree. Its centre is a hollow, but the tree has green leaves and…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A storm tears open an old neem tree. Its centre is a hollow, but the tree has green leaves and carries on growing.
- Which wood has rotted away, the heartwood or the sapwood?
- Why can the tree still send water to its leaves?
- Why is the heartwood slow to rot while the tree is alive?
Need a reminder? The key ideaShow
Spring wood has wide vessels and is light in colour. Autumn wood has narrow vessels and is dark. One spring layer with one autumn layer is an annual ring, and the number of rings gives the age of a tree. Heartwood is the oldest, central wood. It is dead, dark with tannins, resins and oils, and does not conduct. Sapwood is the outer, lighter wood that conducts water and minerals.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) The heartwood. It lies in the centre.
Step 2. (b) Water moves up through the sapwood, which lies outside the heartwood. The sapwood is still there.
Step 3. (c) The heartwood holds tannins, resins and oils, which are poisons to fungi and insects. This keeps it from rotting for a long time.
Answer: (a) heartwood; (b) the sapwood carries the water; (c) its tannins and resins resist attack.
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