The Moonlight Weed is a rare plant that is known to grow in Seek Valley. Its medicinal properties led people to use it mainly as a restorative. During the Toran Liberation War, when Windy used her magic to artificially put the dragons of the Dragon Knights to sleep, the great doctor Liukan asked for some Moonlight Weed in order to create an antidote to cure them.
Tir McDohl and his party traveled to Seek Valley and successfully brought back some Moonlight Weed despite Windy's attempts to stop them. The violent Crystal Core entity stood between Tir and the Moonlight Weed, as well. When Tir's group returned to the Dragon's Den, the antidote could finally be concocted with Black Dragon Orchid and a dragon's liver mixed with the Moonlight Weed.