In mathematics and statistical methods, a tree diagram is used to determine the probability of getting specific results where the possibilities are nested.
In physics, a tree diagram is an acyclic connected Feynman diagram.
In linguistics, a parse tree is one way to visually represent the structure of a sentence (see X-bar theory), a syllable, or phonological feature geometry.
In biology: phylogenetics.
A game tree is a tree diagram used to find and analyze potential moves in a game.
A decision tree is used in operations research.
A HyperbolicTree: a visualization method for a graph inspired by hyperbolic geometry.
Source:http://en.wikipedia.org/wiki/Tree_diagram
