Mugwort is known as the witch's herb. Among mugwort's many magickal associations (which includes prophetic dreaming) is the idea that mugwort is both a superior trail marker (pathfinder) and aids in magickal invisibility.
An article at Goddess Garden teaches regarding mugwort:
Mugwort is reputed in magick to help open locks and locate buried treasure.
Mugwort’s most striking claim to fame is its magnetic  character. Often known as the "compass plant", it’s leaves tend to align themselves with the North-South lines of the earth’s magnetic field. It enjoys a reputation for aiding lost travellers, which supports the relationship this plant has with Artemis, the patron of children, the patron of the wood, and a patron of children of all ages lost in the woods.
Priestesses of Artemis to wore clothing that resembled mugwort, having one side green and one side white. Wearing such a reversible tunic, they could turn it white- side-out to be visible in the forest, for staying together and avoiding hunting accidents; or they could turn it green-side-out for camouflage, to blend into the green of the forest and to hide from danger.
Within the Doctrine of Signatures, mugwort has the power to provide "mundane" invisibility, suggesting that it aids in magickal invisibility.
The powers of prophetic pathfinding, of knowing which way to travel (or not travel), and of turning inside out, remind me of the inverted letters nun of Bamidbar 10:35-36.
 mugwort contains copper; it's pollen may elicit allergic reactions