The Conservatory is an area within Dire Maul East. Is is a fertile garden containing numerous treants and lashers, as well as an ancient, Old Ironbark. The door at the end, which leads to the Shrine of Eldretharr, is barred. Old Ironbark will break down this door for you, but only after you have killed Zevrim Thornhoof and broken the curse the satyr has laid upon the ancient.
The Conservatory is located below the Warpwood Quarter, and it is possible to jump down if one is at full health and can handle any monsters at the bottom. The normal entrance is a tunnel placed between the Warpwood Quarter and Hidden Reach, and through a large unnamed area containing Lethtendris, Hydrospawn, and Zevrim himself.