Learn from this simple and easy tutorial on creating a simple vector tree using adobe Illustrator. 8 simple steps. to complete this tutorial.
Mainly using shapes and the pathfinder with some gradients is used to create this VECTOR TREE in Illustrator.

View the TUTORIAL: Create a VECTOR TREE

http://www.ryancoughlin.com/2008/11/03/create-a-simple-vector-tree/