Rex Trulove
Mention of ‘cambium’ is something a person might come across if they are growing bushes or trees, or if they are studying herbalism. The reason is that cambium is exceptionally important to the growth of trees and many bushes. It also contains a high amount of the healthful substances that sometimes have medicinal value. Cambium is nothing less than amazing, though.
What Cambium is
Cambium is often called the inner bark. While this is descriptive and is exactly what cambium is, it doesn’t explain how extraordinary this substance is. Cambium is indeed a layer found between the bark of a tree and the wood of a tree. Many bushes also have a cambium layer, but it is easiest to think mostly about trees.
Not only is cambium located between the bark and the wood, it is responsible for the creation of both. Through cell division, cambium produces wood when the division is toward the center of the tree. When the cell division is away from the center of the tree, a corky protective layer is produced. This is bark.
Cambium and wood
The cambium produces wood in layers and causes a tree to get thicker with age. During the period of the year that the cambium is producing vigorously, the woody layer it makes tends to be light in color. When the cambium slows down in production of wood, the layer of wood tends to be darker. This creates what many people know as ‘tree rings’.
The width of the rings actually shows how good the growing season was when the ring was laid down. This is because if the growing conditions are good, the cambium produces a lot of wood. When the growing conditions are poor, it doesn’t produce as much. In some years, the cambium may produce two rings, which show botanists that growing conditions abruptly went from good to poor then good again.
The thickness of the rings also shows how fast the tree grows. We know that oak trees are slow-growing and the rings show it. They are relatively thin, giving them a packed appearance. Pine, on the other hand, has broad tree rings, which shows that the tree lays down a lot of wood during the growing season. This means that pines are fast growing. This is only general, however. One species of pine, Pinus longaeva, known as the Great Basin Bristlecone Pine, is exceptionally slow growing and long-lived. One of these trees appears to be over 5,000 years old, making it the oldest tree on Earth.
Cambium and bark
The corky layer cambium produces away from the center of the tree has the role of protecting the cambium. It should be noted that while cambium is living, neither wood nor bark is alive. Layers of wood and bark don’t grow as they get older. The wood and the bark do get thicker as the tree ages, but this is because of additional layers of wood and bark that the cambium produces.
This also explains why many trees have smooth bark when they are young, but the bark splits as the tree gets older. Since the bark isn’t very elastic and is being pushed on by a new layer of bark from the inside each time the cambium adds to the bark, the outside bark splits. This is the case with both pines and oaks. With some kinds of trees, such as birch, the outside layer of bark might peel off in paper-like shards.
Cambium and nutrients
Cambium does more than just produce wood, which is the support structure for the tree, and bark, which is the tree’s protection. It is also a transport system, taking water and nutrients from the roots to the leaves and sugar produced in the leaves back to the roots.
This is what makes the cambium sought-after by herbalists. Medicinal substances are concentrated in the cambium. For instance, salicin, the medicinal substance found in willows, is found in the cambium and in the branch tips. There is also salicin in the leaves, but it isn’t as concentrated.
The truly amazing part
All of this makes cambium rather amazing. It produces both wood and bark, it transports water, minerals, and sugar, and it concentrates medicinal substances in a layer. What boggles the mind is that this layer, even on the largest tree, is very thin. In fact, the cambium layer is only one cell thick!
To many people, it isn’t the importance of what cambium does that makes it amazing, but the fact that it can do all of this, but be only one cell thick. Wouldn’t you agree that this is pretty amazing, considering the bulk of a large tree?
Thanks for this very informative article. I did not know this.
My pleasure. A person can actually kill most trees by cutting all the way through to the wood, all the way around the tree, thus severing the cambium. At that point, the tree above the cut is dead, though it can remain green for a little while.
Wow this is such cool trivia about trees. I love to see the old trees and now I know a little more about them. Thank you for this post!
You are quite welcome. I’m of a mind that plants are truly astonishing in many ways. Most people sort of take them for granted, but they are masterpieces in design and workmanship.
Nice post! Nice pictures!
Thank you very much!
A neat read, reminding of the Creator’s infinite power behind the amazing intricacies of nature. I plan to use the cambium layer of a fig tree to air layer branches for rooting new trees this spring. This one tree has probably produced 40 trees for me in the past and I expect to do at least a dozen more.
If you are not familiar with The Senator I thought you might like to see the following: https://www.youtube.com/watch?v=wuMAJGAEMMg
I agree about the amazing power and planning of God. As for the air layering, it is also the properties of cambium that allow English Walnut trees to be grafted onto Black Walnut trees. If the cambium didn’t have its properties, this wouldn’t be possible.
Aren’t those trees amazing! Our neighborhood has a white and pink dogwood combined that way, as well as a brilliant red Japanese maple with a dark purple/black one.
You know that thing about you learn something new every day? This is today’s “something” for me!
The info about tree rings is interesting. If trees can sometimes produce more than one ring in a season, does that mean that counting rings to determine age can produce errors?
Indeed, there can be errors if the age of the tree is based only on the number of rings it has. Early on, it was thought that a tree only produced a ring every year. We now know differently, so the tree ages don’t match. Weather conditions can be so variable that there can be many weeks of cold weather in the middle of summer, abruptly causing the tree to become semi-dormant, producing the dark ring. Alternately, there can be a warming trend in the middle of winter that can cause the tree to start to grow, producing a light ring. If the normal winter weather returns, the tree again stops.
This doesn’t commonly happen, but it does happen.