There be witchery in them branches
In the past, the forked branches of the European Hazel tree (Corylus Avellana) was commonly used by water diviners to detect unground water courses when sinking a well. This practice was famously recounted in Seamus Heaney's poem "The Diviner" and indeed this practice still occurs today to a lesser extent.
When the first European's settled in New England the European Hazel was not available. Therefore, in order for the Diviner to practice his "Witchery" he had to search for another type of branch which might act as a "green aerial" to detect the presence of spring water. The Hamamelis was readily available in New England at that time and it had a similar appearance and characteristics to the European Hazel. Most importantly it worked its water detecting magic with equal ability. The European Settlers therefore dubbed it the Witch Hazel, a name which it retains to this day.
I love Seamus Heaney so I cannot finish this Fun Friday Fact without including his ode to the Water Diviner;
Cut from the green hedge a forked hazel stick
That he held tight by the arms of the V:
Circling the terrain, hunting the pluck
Of water, nervous, but professionally
Unfussed. The pluck came sharp as a sting.
The rod jerked down with precise convulsions,
Spring water suddenly broadcasting
Through a green aerial its secret stations.
The bystanders would ask to have a try.
He handed them the rod without a word.
It lay dead in their grasp till nonchalantly
He gripped the expectant wrists. The hazel stirred.