The Whomping Willow is a large tree that was planted the year the Marauders first started going to Hogwarts. It was planted over a tunnel that leads to the Shrieking Shack, where Remus Lupin always went during his transformations on every full moon while he attended Hogwarts. It waves it branches to attack anything that goes near it. Only Remus Lupin knows the way it was opened by Madam Pomfrey without being attacked. The current people alive that know this exists are Remus Lupin, Harry Potter, Ronald Weasley, Hermione Granger, and Severus Snape.
