The tradition of a decorated Christmas tree in the United States may date back to the Revolutionary War, when homesick Hessian troops cut and decorated fir trees as was their German custom according to the Department of Agriculture. Since then, the Christmas tree, with its forest fragrance and freshness, has come to represent the Yule season.

A fresh Christmas tree is a safe Christmas tree, at least as far as a fire hazard is concerned.

This has been shown in a number of research efforts and demonstrations. So the problem is to buy a tree that is fresh to start with and then to store and use it in a such a way that it will stay fresh.

It is the moisture in the tree that makes it resistant to fire. If you cut your own tree on a tree farm you can be sure of its safety.

A tree with a moisture content of 85 to 90 percent or more can replace the water lost by evaporation from the foliage if its freshly cut butt is kept in fresh water. If a tree has been allowed to dry below 85 percent moisture, however, it will continue to dry out even when it is standing in water.

If you buy a tree that has already been cut, your chances of getting a fresh one are best early in the season; at least there has been less time for someone else to store it improperly. But even if you shop early, your tree may not be fresh.

Unfortunately, there is no quick, easy way of accurately judging freshness of trees on a retail lot. A bright color to the foliage would normally suggest freshness; but if trees have been sprayed with a colorant, color would be misleading. Another indication of freshness is the pliancy or springness of twigs and needles.

But if you are inexperienced at this sort of thing, oif your hands are chilled, or if the needles are wet with rain or sparkling with frost, you are lost.

However, by shopping carefully and avoiding dry lots, you should be able to find a tree that will perform almost as well as a tree right from the farm.

As soon as you can get the tree home, cut off 1 to 1 1/2 inches from the butt and promptly stand the tree in a pail of fresh water.

The best storage place is a cool room or garage, where the tree is out of wind and sun. The butt should be kept in fresh water during storage.

If you store the tree for a week or longer, saw another 1 to 1 1/2 inches off the butt before you display it. This will remove any fouling of the surface that may be have developed after you made the first cut.

For safe, trouble-free display of the tree, a good stand or holder is essential. It must keep the tree erect without tipping and it should have an adequate reservoir for water to keep the tree fresh.

If you get yourself a 5-gallon paint pail a few stones and some sand, you can make a safe container with a good water-holding capacity. Add 4 to 6 inches of water to the pail, immerse the butt of the tree, and wedge it to the center of the pail with stones. Add enough sand to keep the tree erect, and flood the sand with water. By keeping the sand flooded, you will have enough water to last several days if you wish to go away.