Rosemary
Rosemary was connected with the Virgin Mary (because it was thought to be Mary's favourite plant) and people thought that it could protect you from evil spirits. It is also sometimes called the friendship plant and it was the most common garnish put on the boar's head that rich people ate at the main Christmas meal in the Middle ages!
It is also known as the remembrance herb and was used at Christmas as this is the time that we remember the birth of Jesus.
In the late 1700s a special Christmas Rosemary Service was started in Ripon Cathedral School where a red apple, with a sprig of Rosemary in the top of it, was sold by the school boys to the members of the congregation for 2p, 4p or 6p (depending on the size of apple!).