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What Is Cambium?

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  • Written By: Mary McMahon
  • Edited By: O. Wallace
  • Last Modified Date: 24 August 2014
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Cambium is a layer of material inside a plant or tree which consists of actively dividing cells which generate growth for the plant. The cambium is filled with undifferentiated cells which have the ability to differentiate into many different types of cells, depending on where in the plant they are growing. This part of a plant can be vulnerable to damage; if a plant is cut through the cambium or serious injuries occur, the plant may die.

There are actually two kinds of cambia. The vascular cambium is found inside the tissues of the plant, between the xylem and the phloem. It is responsible for the width and outward growth seen as plants mature and grow larger. In trees, it develops in distinct seasonal rings as the amount of nutrients rises and falls, and can be used as a method of dating the age of the tree, in addition to tracking weather patterns. A thin ring indicates that a tree struggled for water and nutrients, while a thick ring illustrates ample supplies of food and water.

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Some vascular plants also have what is known as a bark or cork cambium. This structure is on the outside of the plant, forming a rough outer layer which protects the plant from damage. In the case of the cork tree, the cork is commercially useful, as it can be harvested and used for a variety of purposes. The cork cambium is less vulnerable to damage than the vascular cambium, because it is designed as a form of armor for the plant, and must be able to withstand rough treatment.

This area of a plant's anatomy is of special interest because it can provide so much information about growing conditions for the plant. When conditions are good, the cells in the cambium are stimulated to divide and reproduce rapidly, producing a thick layer. When conditions are poor, the cells may struggle to divide, and the cambium can be thin and irregular. Studying this region of a shrub or tree's internal structures can be one way to learn about growing conditions.

Awareness of this area of plant anatomy is also important for gardeners. They need to create growing conditions which will encourage the steady growth of this area of the plant, and they also need to consider the cambium when they are establishing grafts. Grafting requires careful alignment of the scion and stock being grafted so that their tissues will align. If the various parts of the branch are not aligned, the scion will die from lack of nutrients, or the growth will be irregular.

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Discuss this Article

Emilski
Post 4

We were talking about different types of plants in my biology class today, and it think it is important to note that monocots do not have cambium. Monocots are usually thought of as grasses, but many flowers like lilies, irises, and tulips are also monocots as are palm trees and bamboo.

Since they don't have cambium, they never increase in diameter. My question about it was that if you look at a bamboo plant or a palm tree, they definitely start out wider at the bottom than they do at the top. My teacher told me that this is kind of like an "illusion." They aren't actually growing outward, they just produce less material at the top of the plant to make them more stable.

TreeMan
Post 3

@cardsfan27 - It's not a perfect system correlating tree growth with weather, but it works in many cases.

Basically, trees often go through two growth stages per year - the first period produces what is called early wood, which creates xylem to transport water. Toward the end of the growing season, late wood is created to "seal up" the wood and protect against fires. When looking at a cross section of a tree, early wood will be lighter and usually thicker, whereas late wood will be the dark rings. Each of these are produced by the cambium, but the type of cells depends on the time of year.

In years with a lot of water, you can tell whether the moisture was in the spring or summer depending on which part of the ring is widest. The only problem is that other factors like increased growing space through blown down trees or timber harvest can also produce wider rings. Conversely, if a tree doesn't have much growing space, it will make small rings regardless of water availability.

cardsfan27
Post 2

@Izzy78 - You are right - the main purpose of the cambium is for outward diameter growth. Like the article also says, the location of the cambium determines what cells are made. If it is in the above-ground part of a plant, it will make wood or some other tissue. In the roots, it will make the proper root cells.

For upward growth and stem elongation, plants have what are called meristems. These are also called buds. They are specialized sections of branches or shoots that have special cells that grow lengthwise.

Unfortunately, I'm not a plant expert. What I am interest in is how trees produce growth rings and how people can predict weather from that. Does anyone know?

Izzy78
Post 1

Interesting article. I always wondered what cambium was. I remember hearing about it in biology class along with xylem and phloem, but I guess I never really paid enough attention to what exactly it was.

I'm still not positive about what the major use of cambium is. I understand the bark part. That is clearly for protection. I guess what I am unsure about is what the article calls vascular cambium. Is it only for outward growth? If that is the case, then what helps a tree or other plant grow taller?

If you were to look at a cross section of a plant, would you be able to see the cambium, or is it something that is too small to see with the naked eye?

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