The Spirit of the Tree is featured in the third season Dinosaurs episode "If I Were a Tree". When Earl Sinclair attempts to push down a tree, their spirits switch bodies. Earl winds up in the tree (which now bears his face), while the tree inhabits Earl's body.
The Spirit of the Tree speaks with a cultured, gentle British accent and is courtly, courteous, and extremely concerned about all living things. Naturally, the Spirit's behavior alarms the other members of the Sinclair family, who immediately question "Earl's" sanity. This is exacerbated when the Spirit pours water over his feet, for nourishment, and holds a lengthy conversation with Charlene's wilting potted plant.