A typical Christmas tree
A Christmas tree is one of the most popular traditions associated with the celebration of Christmas. It is normally an evergreen tree decorated with Christmas lights and colorful ornaments during the days around Christmas. An angel or star is often placed at the top of the tree, representing the host of angels or the Star of Bethlehem from the Nativity story.
Trees outside are sometimes decorated, but more often they are put indoors in houses and stores.
The X-Men would decorate their tree while singing Deck the Halls. However, Scott was a terrible singer and Jubilee tried to get the stubborn Logan to join in.
Not all trees are spectacular
Not everyone can a large, bushy tree such as the Morlocks. Leech went to the surface and took a small tree and decorated it with a broken ornament and bows. It was not much but it was all they could get. Unfortunately this excursion caused him to catch a bad cold where he almost died. When waiting for Leech to get better Mariana showed off to the tree to Jubilee. Logan also noted it.