A tree fell across a path at the arboretum during the recent snow storm. They cut the tree to clear the path which revealed its rings. I am reading a book about forests and thought that you would be interested in the following excerpt from the book.
“For all its size and vitality, for all its impressive thickening from year to year, most of the tissue of a tree trunk does not and cannot grow, once it has been formed. The tissue that adds to a tree’s size is confined to a microscopically thin layer, the cambium… As the cambium cells divide, the tree grows in diameter. The new cells formed toward the inside of the tree become wood, or xylem, and the cells on the outside become a layer called the phloem. Cells produced in the spring growing season are usually much larger than those produced in the summer. The small size and density of the summer cells make them look dark. It is the alternation of the dark summer wood with the lighter-colored spring wood of the following year which produces the rings in trees.”
Farb, Peter and The Editors of LIFE. LIFE Nature Library: The Forest. New York, Time Incorporated, 1961.
