The leaves of a mandrake could be used as ingredients in potions. They also had additional magical properties: part of the process by which a wizard or witch became an Animagus was holding the leaf of a mandrake in their mouth for an entire month.
In 1995, while searching for information that would help him survive the Second Task of the Triwizard Tournament, Harry Potter searched books feverishly for references to "water," but generally found unhelpful information such as potions suggestions that mentioned water, along with other ingredients such as mandrake leaves.
- Harry Potter and the Goblet of Fire (First mentioned)
- Harry Potter: The Creature Vault
- Pottermore (Mentioned only)