There are certain plants that are peculiar to Christmas time for different reasons. Two most common ones are Holly and the Christmas tree which is a specie of the pine tree.
Holly is a native tree of central and southern Europe. An old legend says that holly grew under the footsteps of Jesus Christ, and its thorny leaves and red berries symbolize his physical suffering on the cross. This is why holly is known as ‘Christ’s Thorn’ in some countries.
Probably the most recognized decorative Christmas display all over the world. It is possible that the origin of the modern day Christmas tree comes from eleventh century religious plays that featured a “Paradise” tree, which was a prop used to tell the story of Adam and Eve. According to legend, the triangular outline of some pine trees signifies the trinity of Creator, Son, and Holy Spirit.
Not bad ehn?
Still in the spirit, Merry Christmas!
Source: How Stuff Work