Christmas Greens

 The mystic nature of the evergreen predates Christmas itself, back to when it was the more pagan Solstice of Yule holidays. In the late Middle ages, one did not decorate at the end of November, but very soon before Christmas itself, maintaining that the celebration from Christmas to Epiphany was the big deal. They used natural greens to decorate. The Non-Denominational Church considers both Thanksgiving and New Years holy days, so celebrating past January is not done much. 

Just about everyone in Medieval America celebrates Christmas in one manner or another (Or some kind of holiday that means "Christmas", the scientologists just call it "Holiday" in their language), but that wide climactic differences mean they decorate a little differently from place to place. Luckily, the conifer is widespread throughout the entire country. Fir trees in the north, junipers and Virginia pines in the south. Evergreens don't quite have the same profound meaning in the warmer climates of the south--many prefer to be festive with paper lanterns, which are quite popular there, but one can't help but implement the iconic magnolia plant into their greenery.

Mormon culture makes ascetic elegance a priority, but their winters can be surprisingly rough, and they do have proximity to pines, even blue spruces, so they decorating their churches and town squares do provide a much needed boost of morale for a sometimes tough life. They've actually doubled down on elaborate decorations since their liberation from the Yaegars.

The nomads of the great plains are usually not one for decoration or even symbols--they might find most our modern decking of the halls absurdly decadent, even idolatrous. But they are descended from Americans who consider themselves the most traditional Americans, and the funny thing is, the Yuletide season is the time of year they're the most stationary. They want to be as closes to wooded areas as possible, and in the mountains of the west, that usually does mean pie trees and other conifers. Thus, they hold evergreens as symbolically important as their cattle, and okay, they're in camp, so maybe they can string up their wagons and have a communal Christmas tree. They're not at all sentimental about eventually burning it with everything else.