Came accross this and thought it would be of seasonal interest.

In the Norse myth of the mistletoe, the trickster god Loki plotted
against the bright god Baldr, whose mother Frigg had solicited an oath
from every thing of earth, of sea and of sky, that they would not harm
her son. However, Loki saw that the mistletoe was rooted, not in earth
or sea or air, but in the bark of the oak tree, and thus not covered
by Frigg's oath. He fashioned it into the weapon that slew Baldr, "the
greatest evil ever to befall gods or men." This tale reflects the
parasitic nature of the mistletoe, which sends its roots into a host
tree and takes its nourishment from it.

David
At the wet and hail covered end of Swansea Bat