Secret of Christmas tree.

Some holiday traditions are easy to understand:A feast on Thanksgiving to recall our Pilgrim forebears.Fireworks on the Fourth of July to express exuberant pride. Flags on Memorial Day to honor Americans who died in wars.But Christmas trees? That's a puzzle on more grounds than one. There's no mention of festive trees in the Bible story about the birth of Jesus. Nor do they make a lot of practical sense. They're expensive, they don't last long and they present a disposal problem afterward.

Comedian Jim Gaffigan is among those mystified that this time of year, "We go out and chop down a tree and put it in our living room. Kinda sounds like the behavior of a drunk man, really."
A couple of centuries ago, most Americans might have agreed. But today, nothing symbolizes the holiday more than a brightly decorated evergreen.
Every year, more than 30 million real trees are sold in the United States, most of them pines or firs. That's along with nearly 10 million artificial ones. There's a whole industry attached: Upward of a million acres of land in this country are used for Christmas tree farms.