Holly:

Medieval monks called this plant the Holy Tree. They believed Holly would keep evil spirits away, and protect their home from lightening. The early Romans decorated their hallways with garlands made from Holly for their mid-winter feast, Saturnalia.
Later its pointed leaves represented the crown of thorns worn by Jesus, and the red berries his drops of blood. Holly signified eternal life, and also represented the biblical burning bush in the Old Testament, when God appeared before Moses.