Holly

Holly was very important to the Druids and Romans at their winter solstice celebrations but it is now a plant traditionally associated with several legends of its origins at the first Christmas.
An old carol:

The holly and the ivy,
When they are both full grown
Of all the trees that are in the wood
The holly bears the crown.

The holly bears a blossom
As white as lily flower
And Mary bore sweet Jesus Christ
To be our sweet Saviour.

The holly bears a berry
As red as any blood,
And Mary bore sweet Jesus Christ
To do poor sinners good.

The holly bears a prickle
As sharp as any thorn,
And Mary bore sweet Jesus Christ
On Christmas Day in the morn.

The holly bears a bark
As bitter as any gall,
And Mary bore sweet Jesus Christ
For to redeem us all.

The holly and the ivy,
When they are both full grown
Of all the trees that are in the wood
The holly bears the crown.

David Beaulieu has interpreted it as:

Holly's "white as lily" flower in the second stanza is an allusion to Christ's purity, through Mary.
In the third stanza, a correlation is drawn between the red color of holly's berry and Christ's blood.
Holly's thorny "prickle" in the fourth stanza is an allusion to the "crown of thorns" worn by Christ.
And the bitter taste of holly's bark mentioned in the fifth stanza? This could be a reference to the drink offered Christ as he hung on the cross.