moonwort
(_Botrychium lunaria_), which was said to open locks and to unshoe
horses that trod on it, a notion which Du Bartas thus mentions in his
"Divine Weekes"--

"Horses that, feeding on the grassy hills,
Tread upon moonwort with their hollow heels,
Though lately shod, at night go barefoot home,
Their maister musing where their shoes become.
O moonwort! tell me where thou bid'st the smith,
Hammer and pinchers, thou unshodd'st them with.

Alas! what lock or iron engine is't,
That can thy subtle secret strength resist,
Still the best farrier cannot set a shoe
So sure, but thou (so shortly) canst undo."

The blasting-root, known in Germany as spring-wurzel, and by us as
spring-wort, possesses similar virtues, for whatever lock is touched by
it must yield. It is no easy matter to find this magic plant, but,
according to a piece of popular folk-lore, it is obtained by means of
the woodpecker. When this bird visits its nest, it must have been
previously plugged up with wood, to remove which it goes in search of
the spring-wort. On holding this before the nest the wood shoots out
from the tree as if driven by the most violent force. Meanwhile, a red
cloth must be placed near the nest, which will so scare the woodpecker
that it will let the fabulous root drop. There are several versions of
this tradition. According to Pliny the bird is the raven; in Swabia it
is the hoopoe, and in Switzerland the swallow. In Russia, there is a
plant growing in marshy land, known as the rasir-trava, which when
applied to locks causes them to open instantly. In Iceland similar
properties are ascribed to the herb-paris, there known as lasa-grass.

According to a piece of Breton lore, the selago, or "cloth of gold,"
cannot be cut with steel without the sky darkening and some disaster
taking place:--

"The herb of gold is cut; a cloud
Across the sky hath spread its shroud
To war."

On the other hand, if properly gathered with due ceremony, it conferred
the power of understanding the language of beast or bird.[2] As far back
as the time of Pliny, we have directions for the gathering of this magic
plant. The person plucking it was to go barefoot, with feet washed, clad
in white, after having offered a sacrifice of bread and wine. Another
plant which had to be gathered with special formalities was the magic
mandragora. It was commonly reported to shriek in such a hideous manner
when pulled out of the earth that,