Russell Holdstein, age 12, Cleveland, Ohio, for his questions

Does a tree ever stop growing?

A tree goes on growing all its life. The growth cells circle the trunk.. dust below the bark. In every growing season, each growth cell splits lengthwise down the middle and becomes two cells. Usually, the cell on the outside than becomes a growth cell. Ring after ring of new wood cells is added around the trunk of the tree and this goes on throughout the 1ife of the tree.

The tree begins life as  a slender sapling. Each year it gets stouter as a new circle of wood is  added around its trunk. In times all the fetch and carry work is done by the new wood cells around the outer edge of the trunk. The central  wood becomes dry and hard, Its only fob is to support the lofty branches  of the tree.

The heartwood in the center of the trunk is actually dead wood. Because it is dry and hard, it is often attacked by beetles, birds or bacteria. It may become chewed up and crumble away. Then we have a hollow tree, a tree with a hole in the center of its trunk. Rodents and other animals like to hide in a hollow tree and this helps to enlarge the hole. The true becomes an apartment house for woodland creatures.

This does not bother. the tree at all. It will go on living and growing so long as there is a sturdy trunk to support its branches and a connected system of new wood to carry sap to and fro. Every season, new wood will be added around the trunk. And these new cells carry up moisture from the roots and distribute the food‑bearing sap,

Trees do not die of old age, tin old hollow tree may  collapse, tit any age a tree may be attacked and destroyed by disease. A porcupine may come along and chew off a ring of bark clear around the trunk of the tree,

This unfortunate tree will die. Some trees are felled by storms and some by the lumberman's ax, But so long as the tree has a connected network of new wood cells to fetch and carry  it will grow.

Since a tree adds new wood each year, we would expect the oldest trees to be the biggest trees. In the main this is true. Until recently, everyone thought the oldest trees were the giant Sequoias of California. The giant of these giants is called General Sherman. The General stands in Sequoia National Perk in the Sierra Nevada Mountains. He is 275 foot tall, end. is estimated to be 3500 years old.

The General may still b o the biggest tree in the world. But we have recently discovered that he is not the oldest about 100 miles north of the Sequoias there are still older trees. And these fellows are small and twisted dwarfs. These ancient trees have learned to live in harsh conditions of cola and drought, adding only a few cells at a time. They are the bristlecone pines; several of them are over 4,000 years old. And one of them is about 1,600 years old.