In Their Eyes Were Watching God, Hurston writes, "Like a great tree in leaf with the things suffered, things enjoyed, things done and undone." What might this metaphor mean?
That's a simile and not a metaphor, right? The full sentence has the narrator comparing the life of Janie to a tree in Zora Neale Hurston's novel Their Eyes Were Watching God:
Janie saw her life like a great tree in leaf with the things suffered, things done and undone. Dawn and doom was in the branches.
The passage comes from the opening of chapter two, I believe, and that chapter is full of tree imagery. Janie's awakening sexuality, in perhaps the most talked about passage in the novel, is likened to a pear tree in blossom, and Janie's grandmother, who grew up in slavery, is likened to a tree with branches but no roots.
The tree tropes in the novel -- some of them are similes, some metaphors, and some even symbols -- all suggest the idea of growth, of branching, of the development of the individual and the family, of naturalness, and so on. Similes, metaphors, and symbols have power because they don't have to contain just one single meaning. You've asked a good question!