Cambium

This are the rings of the inside of a tree. The inside of a tree is an example of cambium. Cambium is a cellular plant tissue which grows layers of phloem, xylem, or cork by division. This growth promotes stem widening, or growth in diameter which is why it is most common in woody trees. Cambium also works to repair damage to a part of the plant, mostly in woody plants. The repair then promotes new cells to grow in the damaged area. Cambium is essentially the targeted repair-man of some plants and trees. It can sometimes last the whole lifetime of a plant/tree!