Bone Orchards are a creation of Avassh, the Twister of Roots. They are a plant that sprouts from the bones of humanoids, which grow into trees that appear dead, with bark the texture of bone. These trees feed on the vestiges of the spirit of the bones that they sprouted from, and seem to contain some kind of consciousness related to the dead. Bone Orchards are a valid target for speak with dead and similar magic, behaving as if the corpse at their roots was the target. Even without this magic, spirits seem to linger near bone orchards, and the whispers of the dead can often be heard in their presence.
Most bone orchards that exist today date back to the daelkyr war with the Dhakaani empire, but occasionally new ones sprout in areas with Avassh's influence.