Used in the Wiggenweld Potion (PS/g, CS/g, HBP/g).
Similar to silvery "moon-dew" with magical properties mentioned in the 1997 German children's novel Dragon Rider by Cornelia Funke. The blue flowers that provide the moon-dew are known as "dragon flowers."
"...The dew that on any moonlit night gathers on the blue flowers growing by the lake. If you lick it off the petals and leaves, you can fly by night as well as by day."