Evergreen spores can aggravate allergies.

• Position: Christmas Trees - Mountain cedar pollen's mold spores particularly allergenic - Brief Article

An evergreen tree, decorated and fragrant, conjures up Christmas for many people. However, for the estimated one person in 10 who is allergic to mountain-cedar pollen, a live tree can be a harbinger of holiday misery. Evergreen, a member of the juniper family, and some of its close relatives remain popular as Christmas trees--especially among people who like to cut clown their own, reports Dave Khan, associate professor of internal medicine at the University of Texas Southwestern Medical Center at Dallas.

"During late November, mountain cedars begin releasing airborne pollen, the trees' fertilizing agent. Fortunately, the Scotch pines and Douglas firs that are the mainstays of most Christmas-tree lots don't pollinate in the winter. But any live Christmas tree can...