Illustration in A Guide Book to the Great Tree
Blackfire Mushrooms are a kind of mushroom with black tops that look like clams and a yellow stalk. When touched, they spew a fine, black powder. They are very deadly to trees. When the mushrooms get into its roots, it would spread burning streaks on it, which will cause the tree to die. A younger tree would only take a year to die, whereas n older and stronger one can survive several years before it meets its fate.The mushrooms could be killed off by using a potion made from a herb called Lyssop.
The Great Ga'Hoole Tree was once affected by Blackfire. A group of owls from the Ga'Hoolology Chaw went around the kingdom to gain information on the mushrooms and how to fight it. Aude the Snowy Owl, a tree healer, told of the cause and the cure. The Dark Sisters, a group of nest-maid blind snakes that specialize in potions, developed the potion made from Lyssop. Within two weeks, the streaks and the mushrooms disappeared from the tree.