First lady Michelle Obama (R), joined by daughters Sasha Obama (C) and Malia Obama, is presented with the official White House Christmas Tree on November 25, 2011 in Washington, DC. The tree, a 19-foot-tall balsam fir, was grown on Schroeder's Forevergreens farm near Neshkoro, Wisconsin. (Photo by Brendan Hoffman/Getty Images)

U.S. Army Sgt. Patricia Foust receives a free Christmas tree on December 7, 2011 at Fort Carson in Colorado Springs, Colorado. More than 600 soldiers and military families at the base chose trees as part of the annual Trees for Troops program. (Photo by John Moore/Getty Images)

Employee Sandra Jaeckel, at the photographer's request, adjusts a ribbon around the neck of a giant chocolate Easter bunny at the production facility at Confiserie Felicitas chocolates maker on April 9, 2014 in Hornow, Germany. Easter is among the busiest times of year for the chocolatier, which produces Easter bunnies and eggs in a wide variety of sizes and styles. Founded by Belgian expats Goedele Matthyssen and Peter Bientsman the company will soon celebrate its 21st year. (Photo by Sean Gallup/Getty Images)

Emergency services work at the scene of a bus accident on the Kingsway in central London February 2, 2015. A number 91 double-decker bus had its roof ripped off after hitting a tree, causing injury to passengers and passers-by, local media reported. (Photo by Peter Nicholls/Reuters)

In this April 23, 2015 photo, friends Jia Haixia, left, and Jia Wenqi work to plant a tree in a field in Yeli village near Shijiazhuang city in northern China's Hebei province. For the past 13 years, Jia Wenqi, who has no arms, and Jia Haixia, who is blind, have worked together to plant and water more than 12,000 trees near their village. (Photo by Helene Franchineau/AP Photo)

The space shuttle Endeavour is transported to the California Science Center in Exposition Park from Los Angeles International Airport (LAX) in Los Angeles, California. (Photo by Kevork Djansezian)