A thick twig has a periderm. Its cells are made by one meristem…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A thick twig has a periderm. Its cells are made by one meristem.
- Name that meristem.
- Name the layer made on its outer side and the layer made on its inner side.
- Which of these two layers is dead at maturity?
Need a reminder? The key ideaShow
The cork cambium (phellogen) arises in the cortex and cuts off cells on both sides. Outward it makes the cork (phellem), whose dead cells have suberin in their walls and form a waterproof cover. Inward it makes the phelloderm (secondary cortex), made of living cells. The three make the periderm. A lenticel is a patch of loosely arranged cells in the cork, and it lets gases pass. Bark means all the tissues outside the vascular cambium.
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 cork cambium, or phellogen.
Step 2. (b) Outward it makes the cork, or phellem. Inward it makes the phelloderm.
Step 3. (c) The cork. Its cells have suberin in their walls and die.
Answer: (a) cork cambium; (b) cork outside, phelloderm inside; (c) cork.
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