They worship the FEV mutant Harold, who became one with the tree Bob (which Harold likes to tease by calling Herbert) that started growing from his head sometime before 2241, but after 2161. The Treeminders have renounced using technology (although they see guns as a necessary evil to protect Oasis) and live off of the gifts from the trees that grow around Oasis. They do not seem to understand Harold's wishings for them to kill him as some of them see it as a riddle such as Tree Father Birch. All of the Treeminders are named after different species of trees.
The Treeminders consist of:
The Treeminders appear in Fallout 3.