In the story, Hermes gave this herb to Odysseus to protect him from Circe's magic when he went to her home to rescue his friends. These friends came together with him from the island Aiolos after they escaped from the Cyclops. "The plant 'moly' of which Homer speaks; this plant, it is said, had grown from the blood of the Giant Picolous killed in the isle of Kirke; it has a white flower; the ally of Kirke who killed Picolous was Helios (the Sun); the combat was hard (Greek malos) from which came the name of this plant" Homer also describes Moly by saying "The root was black, while the flower was as white as milk; the gods call it Moly, dangerous for a mortal man to pluck from the soil, but not for the deathless gods. All lies within their power".
Since Gigantes could only be destroyed with the assistance of a hero this would make the Gigantes indestructible. When the Gigante, Molios, was defeated, his blood was collected by his mother Gaia and sprung this plant, which made the Gigantes invulnerable. This was notified to Zeus, who ordered Helios, Selene and Eos don't to bright in the sky while the plant still in the earth. Then, the gods started to look for the plant in the night and the destroyed all the plants.