PUYALLUP, Wash. - Katie Coats used to work in a crime lab in Seattle. These days, she reports to a quieter research facility about 40 miles south, in the shadow of Mount Rainier.

Here, Coats wields a surgical blade on her subjects, slicing away small chunks of cells and delicately dropping them in vials to preserve for genetic analysis.

Coats isn't trying to chase down rapists or serial killers. She's using the tissue - which, on a recent day, came from a Canaan fir - to make better Christmas trees.

Or so her boss, plant pathologist Gary Chastagner, hopes.

It's tempting to think the evergreen in your living room is a pristine piece of nature, plucked from a silent and snowy hillside.

In fact, for at least the last 30 years, the majority of American Christmas trees have come from farms, planted in methodically managed rows and tended on a rigorous schedule. They have been bred to have that crisp clean mountain smell and that fresh bluish hue. They've been sheared to get those thick, brushy needles and that tight conical shape.

And a small cadre of researchers such as Chastagner has been perfecting them in the lab, too.

These sleuths have spent decades counting and measuring needles and branches, sometimes setting up pop-up labs near Christmas tree lots. Like champion rose growers, they nurture the beauties and weed out the "Charlie Brown trees" that are oddly shaped, or trees that grow too slowly or fall prey to pests.

Armed with a $1.3 million grant from the U.S. Department of Agriculture, Chastagner and his fellow Christmas tree scientists are adding genetic analysis to their arsenal. Their goal is to pinpoint why some trees turn out better than others.

The researchers don't expect consumers to share their interest in tree taxonomies - what makes a spruce different from a pine, or a Douglas fir - not really a "true" fir, they note - different from a balsam, Fraser or noble fir.

"They may know, 'I bought this tree last year, it was a noble fir, I liked the strong branches,' " Chastagner said. "Or they may know, 'I grew up with a Douglas fir and I liked how it smells.' "

His real concern, he added, is that no matter what tree a shopper picks, it does not have any of the annoying inconveniences that make people turn to artificial trees instead of the real thing.

It may not approach the seriousness of halting climate change, but Chastagner sees his quest as a matter of survival for the U.S. Christmas tree industry, which employs about 100,000 people and brings in more than $1 billion a year.

According to the National Christmas Tree Association, Americans bought 30.8 million farm-grown Christmas trees in 2011, spending an average of $34.87.

Those numbers haven't changed much in the last 50 years, even as the number of U.S. households has grown and tree quality has improved, Chastagner said. In the meantime, sales of "plastic tree-shaped decorations," as a spokesman for the National Christmas Tree Association calls them, have been creeping up.