For many centuries this plant has been the base of a range of remedies, so much so that it is also known as 'all-heal'. It is a parasitic plant. When the host or main tree died off in winter it was believed that the mistletoe held the life of the main plant within itself.
If found growing on an oak tree this had great significance for the Druid who revered the oak as much as the rowan. the druids viewed the berries of the mistletoe when found on an oak tree as the seminal fluid of the oak-tree god (or spirit).
So it was thought that this effect was then an indicator of a charm to induce fertility in action. The mistletoe was cut on the sixth day of the moon with a golden sickle and with full ceremony, which was then divided amongst the people.
Fastening the mistletoe to a doorway was thought to ward off all evil, and thunder and lightening. Perhaps the modern custom of kissing under the mistletoe at Christmas is a remnant of this pagan custom. The sprigs of this plant were regarded as a symbol by some of hospitality.